ORCID Profile
0000-0002-7856-8566
Current Organisation
University of Queensland
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Medicinal and Biomolecular Chemistry | Biological And Medical Chemistry | Proteins and Peptides | Biochemistry And Cell Biology Not Elsewhere Classified | Biologically Active Molecules | Enzymes | Structural Biology (incl. Macromolecular Modelling) | Bioinorganic Chemistry | Characterisation of Biological Macromolecules | Structural Chemistry | Biochemistry and Cell Biology | Organic Chemical Synthesis | Chemical Characterisation of Materials | Medical Biochemistry: Proteins And Peptides | Inorganic Chemistry | Condensed Matter Physics | Organic Chemical Synthesis | Chemical Sciences Not Elsewhere Classified | Nanochemistry and Supramolecular Chemistry | Toxicology (Incl. Clinical Toxicology) | Clinical Chemistry | Protein Targeting And Signal Transduction | Medicinal and Biomolecular Chemistry not elsewhere classified | Nonlinear Optics and Spectroscopy | Organic Chemistry | Pharmacology Not Elsewhere Classified | Separation Science | Macromolecular and Materials Chemistry | Transition Metal Chemistry | Cheminformatics and Quantitative Structure-Activity Relationships | Theoretical and Computational Chemistry | Physical Chemistry (Incl. Structural) | Quantum Chemistry | Biotechnology Not Elsewhere Classified | Theory Of Materials | Condensed Matter Imaging | Bioinformatics
ANZSRC Socio-Economic Objective (SEO)
Chemical sciences | Treatments (e.g. chemicals, antibiotics) | Biological sciences | Expanding Knowledge in the Chemical Sciences | Expanding Knowledge in the Biological Sciences | Education and Training not elsewhere classified | Diagnostics | Human Pharmaceutical Treatments (e.g. Antibiotics) | Control of Animal Pests, Diseases and Exotic Species in Farmland, Arable Cropland and Permanent Cropland Environments | Physical sciences | Resourcing of Education and Training Systems | Prevention—biologicals (e.g. vaccines) | Crop and animal protection chemicals | Infectious diseases | Nervous system and disorders | Cardiovascular system and diseases | Cancer and related disorders | Expanding Knowledge in the Medical and Health Sciences | Scientific instrumentation | Expanding Knowledge in the Physical Sciences | Scientific Instruments |
Related Links
Publications
Profiling the anti-protozoal activity of anti-cancer HDAC inhibitors against Plasmodium and Trypanosoma parasites
Publisher: Elsevier BV
Date: 12-2015
Cu(II) Potentiation of Alzheimer Aβ Neurotoxicity
Publisher: Elsevier BV
Date: 12-1999
C5aR and C5L2 act in concert to balance immunometabolism in adipose tissue
Publisher: Elsevier BV
Date: 2014
DOI: 10.1016/J.MCE.2013.10.019
Abstract: Recent studies suggested that the immunometabolic receptors C5aR and C5L2, constitutively self-associate into homo-/heterodimers and that acylation stimulating protein (ASP/C3adesArg) or C5a treatment of adipocytes increased their colocalization. The present study evaluates the C5aR contribution in adipocytes to the metabolic and immune responses elicited by ligand stimulation. The effects of C5a, ASP, and insulin on cytokine production, triglyceride synthesis (TGS), and key signaling pathways were evaluated in isolated primary adipocytes and cultured 3T3-L1 differentiated adipocytes. In addition, mRNA expression of IRS1 and PGC1α was compared in adipose tissue s les from WT vs. C5aRKO mice. Both C5a and ASP directly increased MCP-1 (238±4% P<0.001, and 377±2% vs. basal 100% P<0.001, respectively) and KC (413±11% P<0.001, and 529±16% P<0.001 vs. basal 100%, respectively) secretion, TGS (131±1% P<0.001, and 152±6% P<0.001, vs. basal 100% respectively), and Akt/NFκB phosphorylation pathways in adipocytes. However, in C5aRKO adipocytes, C5a effects were disrupted, while stimulatory effects of ASP were mostly maintained. Addition of C5a completely blocked ASP signaling and activity in both C5aRKO and WT adipocytes as well as 3T3-L1 adipocytes. Furthermore, C5aRKO adipocytes revealed impaired insulin stimulation of cytokine production, with partial impairment of signaling and TGS stimulation, consistent with decreased IRS1 and PGC1α mRNA expression in adipose tissue. These observations indicate the importance of C5aR in adipose tissue metabolism and immunity, which may be regulated through heterodimerization with C5L2.
Facile synthesis of mono- and bis-methylated Fmoc-Dap, -Dab and -Orn amino acids
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C4CC09780G
Abstract: A facile selective synthesis of mono and bis methylated Fmoc-Dap, -Dab and -Orn amino acids in a one-pot process.
Inhibitors of β-amyloid formation based on the β-secretase cleavage site
Publisher: Elsevier BV
Date: 02-2000
A new paradigm for protein kinase inhibition: blocking phosphorylation without directly targeting ATP binding.
Publisher: Elsevier BV
Date: 08-2007
DOI: 10.1016/J.DRUDIS.2007.06.008
Abstract: Protein kinases are now recognised as an important class of drug targets. Whilst many protein kinase inhibitors directly interact with the ATP-binding site, Gleevec is a notable ex le from a new class of allosteric inhibitors that alter protein kinase conformation to block productive ATP binding. Recently, kinase inhibitors with different mechanisms of action have also been described. Some of these are allosteric inhibitors that alter kinase conformation and prevent protein substrate binding. Other inhibitors directly compete with protein substrate binding. These inhibitors promise exciting therapeutic opportunities by exploiting new mechanisms of action and may thus allow greater specificity in protein kinase inhibition with fewer off-target side effects.
Structure, function and pathophysiology of protease activated receptors
Publisher: Elsevier BV
Date: 06-2011
DOI: 10.1016/J.PHARMTHERA.2011.01.003
Abstract: Discovered in the 1990s, protease activated receptors(1) (PARs) are membrane-spanning cell surface proteins that belong to the G protein coupled receptor (GPCR) family. A defining feature of these receptors is their irreversible activation by proteases mainly serine. Proteolytic agonists remove the PAR extracellular amino terminal pro-domain to expose a new amino terminus, or tethered ligand, that binds intramolecularly to induce intracellular signal transduction via a number of molecular pathways that regulate a variety of cellular responses. By these mechanisms PARs function as cell surface sensors of extracellular and cell surface associated proteases, contributing extensively to regulation of homeostasis, as well as to dysfunctional responses required for progression of a number of diseases. This review examines common and distinguishing structural features of PARs, mechanisms of receptor activation, trafficking and signal termination, and discusses the physiological and pathological roles of these receptors and emerging approaches for modulating PAR-mediated signaling in disease.
Profiling the enzymatic properties and inhibition of human complement factor B
Publisher: Elsevier BV
Date: 11-2007
Crystal Structure of the Dithiol Oxidase DsbA Enzyme from Proteus Mirabilis Bound Non-covalently to an Active Site Peptide Ligand
Publisher: Elsevier BV
Date: 07-2014
Comparative protection against rat intestinal reperfusion injury by a new inhibitor of sPLA 2, COX-1 and COX-2 selective inhibitors, and an LTC 4 receptor antagonist
Publisher: Wiley
Date: 09-2003
Insights to substrate binding and processing by West Nile Virus NS3 protease through combined modeling, protease mutagenesis, and kinetic studies
Publisher: Elsevier BV
Date: 12-2006
Novel helix-constrained nociceptin derivatives are potent agonists and antagonists of ERK phosphorylation and thermal analgesia in mice
Publisher: American Chemical Society (ACS)
Date: 10-11-2010
DOI: 10.1021/JM101139F
Abstract: The nociceptin opioid peptide receptor (NOP, NOR, ORL-1) is a GPCR that recognizes nociceptin, a 17-residue peptide hormone. Nociceptin regulates pain transmission, learning, memory, anxiety, locomotion, cardiovascular and respiratory stress, food intake, and immunity. Nociceptin was constrained using an optimized helix-inducing cyclization strategy to produce the most potent NOP agonist (EC50 = 40 pM) and antagonist (IC50 = 7.5 nM) known. Alpha helical structures were measured in water by CD and 2D (1)H NMR spectroscopy. Agonist and antagonist potencies, evaluated by ERK phosphorylation in mouse neuroblastoma cells natively expressing NOR, increased 20-fold and 5-fold, respectively, over nociceptin. Helix-constrained peptides with key amino acid substitutions had much higher in vitro activity, serum stability, and thermal analgesic activity in mice, without cytotoxicity. The most potent agonist increased hot plate contact time from seconds up to 60 min the antagonist prevented this effect. Such helix-constrained peptides may be valuable physiological probes and therapeutics for treating some forms of pain.
Protease-activated receptor-2 peptides activate neurokinin-1 receptors in the mouse isolated trachea
Publisher: American Society for Pharmacology & Experimental Therapeutics (ASPET)
Date: 24-01-2006
Abstract: Protective roles for protease-activated receptor-2 (PAR(2)) in the airways including activation of epithelial chloride (Cl(-)) secretion are based on the use of presumably PAR(2)-selective peptide agonists. To determine whether PAR(2) peptide-activated Cl(-) secretion from mouse tracheal epithelium is dependent on PAR(2), changes in ion conductance across the epithelium [short-circuit current (I(SC))] to PAR(2) peptides were measured in Ussing chambers under voltage cl . In addition, epithelium- and endothelium-dependent relaxations to these peptides were measured in two established PAR(2) bioassays, isolated ring segments of mouse trachea and rat thoracic aorta, respectively. Apical application of the PAR(2) peptide SLIGRL caused increases in I(SC), which were inhibited by three structurally different neurokinin receptor-1 (NK(1)R) antagonists and inhibitors of Cl(-) channels but not by capsaicin, the calcitonin gene-related peptide (CGRP) receptor antagonist CGRP(8-37), or the nonselective cyclooxygenase inhibitor indomethacin. Only high concentrations of trypsin caused an increase in I(SC) but did not affect the responses to SLIGRL. Relaxations to SLIGRL in the trachea and aorta were unaffected by the NK(1)R antagonist nolpitantium (SR 140333) but were abolished by trypsin desensitization. The rank order of potency for a range of peptides in the trachea I(SC) assay was 2-furoyl-LIGRL > SLCGRL > SLIGRL = SLIGRT > LSIGRL compared with 2-furoyl-LIGRL > SLIGRL > SLIGRT > SLCGRL (LSIGRL inactive) in the aorta relaxation assay. In the mouse trachea, PAR(2) peptides activate both epithelial NK(1)R coupled to Cl(-) secretion and PAR(2) coupled to prostaglandin E(2)-mediated smooth muscle relaxation. Such a potential lack of specificity of these commonly used peptides needs to be considered when roles for PAR(2) in airway function in health and disease are determined.
Alpha-synuclein structure and Parkinson’s disease – lessons and emerging principles
Publisher: Springer Science and Business Media LLC
Date: 22-07-2019
PAR2 Modulators Derived from GB88
Publisher: American Chemical Society (ACS)
Date: 21-10-2016
Novel cylindrical, conical, and macrocyclic peptides from the cyclooligomerization of functionalized thiazole amino acids [2]
Publisher: American Chemical Society (ACS)
Date: 19-12-2001
DOI: 10.1021/JA002666Z
Human MAIT cell cytolytic effector proteins synergize to overcome carbapenem resistance in Escherichia coli
Publisher: Cold Spring Harbor Laboratory
Date: 16-01-2020
DOI: 10.1101/2020.01.16.908806
Abstract: Mucosa-associated invariant T (MAIT) cells are abundant antimicrobial T cells in humans, and recognize antigens derived from the microbial riboflavin biosynthetic pathway presented by the MHC-Ib-related protein (MR1). However, the mechanisms responsible for MAIT cell antimicrobial activity are not fully understood, and the efficacy of these mechanisms against antibiotic resistant bacteria has not been explored. Here, we show that MAIT cells mediate MR1-restricted antimicrobial activity against E. coli clinical strains in a manner dependent on the activity of cytolytic proteins, but independent of production of pro-inflammatory cytokines or induction of apoptosis in infected cells. The combined action of the pore-forming antimicrobial protein granulysin and the serine protease granzyme B released in response to TCR-mediated recognition of MR1-presented antigen is essential to mediate control against both cell-associated and free-living E. coli . Furthermore, MAIT cell-mediated bacterial control extend to multidrug-resistant E. coli primary clinical isolates additionally resistant to carbapenems, a class of last resort antibiotics. Notably, high levels of granulysin and granzyme B in the MAIT cell secretomes directly damage bacterial cells by increasing their permeability, rendering initially resistant E. coli susceptible to the bactericidal activity of carbapenems. These findings define the role of cytolytic effector proteins in MAIT cell-mediated antimicrobial activity, and indicate that granulysin and granzyme B synergize to restore carbapenem bactericidal activity and overcome carbapenem resistance in E. coli . Potent antimicrobial activity of human MAIT cells overcomes carbapenem-resistance in control of Escherichia coli
Identification of brain metastasis genes and therapeutic evaluation of histone deacetylase inhibitors in a clinically relevant model of breast cancer brain metastasis
Publisher: Cold Spring Harbor Laboratory
Date: 06-04-2018
DOI: 10.1101/296384
Abstract: Breast cancer brain metastasis remains largely incurable. While several mouse models have been developed to investigate the genes and mechanisms regulating breast cancer brain metastasis, these models often lack clinical relevance since they require the use of immune-compromised mice and/or are poorly metastatic to brain from the mammary gland. We describe the development and characterisation of an aggressive brain metastatic variant of the 4T1 syngeneic model (4T1Br4) that spontaneously metastasises to multiple organs, but is selectively more metastatic to the brain from the mammary gland than parental 4T1 tumours. By immunohistochemistry, 4T1Br4 tumours and brain metastases display a triple negative phenotype, consistent with the high propensity of this breast cancer subtype to spread to brain. In vitro assays indicate that 4T1Br4 cells have an enhanced ability to adhere to or migrate across a brain-derived endothelial monolayer and greater invasive response to brain-derived soluble factors compared to 4T1 cells. These properties are likely to contribute to the brain-selectivity of 4T1Br4 tumours. Expression profiling and gene set enrichment analyses demonstrate the clinical relevance of the 4T1Br4 model at the transcriptomic level. Pathway analyses implicate tumour-intrinsic immune regulation and vascular interactions in successful brain colonisation, revealing potential therapeutic targets. Evaluation of two histone deacetylase inhibitors, SB939 and 1179.4b, shows partial efficacy against 4T1Br4 metastasis to brain and other sites in vivo and potent radio-sensitising properties in vitro . The 4T1Br4 model provides a clinically relevant tool for mechanistic studies and to evaluate novel therapies against brain metastasis. We introduce a new syngeneic mouse model of spontaneous breast cancer brain metastasis, demonstrate its phenotypic, functional and transcriptomic relevance to human TNBC brain metastasis and test novel therapies.
A class of γδ T cell receptors recognize the underside of the antigen-presenting molecule MR1
Publisher: American Association for the Advancement of Science (AAAS)
Date: 20-12-2019
Abstract: The ligands bound by γδ T cell receptors (TCRs) are less well characterized than those of their αβ TCR cousins, which are antigens presented by major histocompatibility complex (MHC) and related proteins. Le Nours et al. identified a phenotypically erse γδ T cell subset in human tissues that reacts to MHC-related protein 1 (MR1), which presents vitamin B derivatives. A crystal structure of a γδ TCR–MR1–antigen complex revealed that some of these TCRs can bind underneath the MR1 antigen-binding cleft instead of recognizing the presented antigen. This work thus uncovers an additional ligand for γδ T cells and reconceptualizes the nature of T cell antigen recognition. Science , this issue p. 1522
Mucosal-associated invariant T-cell activation and accumulation after in vivo infection depends on microbial riboflavin synthesis and co-stimulatory signals
Publisher: Elsevier BV
Date: 2017
DOI: 10.1038/MI.2016.39
Abstract: Despite recent breakthroughs in identifying mucosal-associated invariant T (MAIT) cell antigens (Ags), the precise requirements for in vivo MAIT cell responses to infection remain unclear. Using major histocompatibility complex-related protein 1 (MR1) tetramers, the MAIT cell response was investigated in a model of bacterial lung infection employing riboflavin gene-competent and -deficient bacteria. MAIT cells were rapidly enriched in the lungs of C57BL/6 mice infected with Salmonella Typhimurium, comprising up to 50% of αβ-T cells after 1 week. MAIT cell accumulation was MR1-dependent, required Ag derived from the microbial riboflavin synthesis pathway, and did not occur in response to synthetic Ag, unless accompanied by a Toll-like receptor agonist or by co-infection with riboflavin pathway-deficient S. Typhimurium. The MAIT cell response was associated with their long-term accumulation in the lungs, draining lymph nodes and spleen. Lung MAIT cells from infected mice displayed an activated/memory phenotype, and most expressed the transcription factor retinoic acid-related orphan receptor γt. T-bet expression increased following infection. The majority produced interleukin-17 while smaller subsets produced interferon-γ or tumor necrosis factor, detected directly ex vivo. Thus the activation and expansion of MAIT cells coupled with their pro-inflammatory cytokine production occurred in response to Ags derived from microbial riboflavin synthesis and was augmented by co-stimulatory signals.
Inhibitors selective for HDAC6 in enzymes and cells
Publisher: Elsevier BV
Date: 12-2010
DOI: 10.1016/J.BMCL.2010.09.100
Abstract: Histone deacetylase inhibitors with anticancer or anti-inflammatory activity bind to Class I or Class I and II HDAC enzymes. Here we compare selectivity of inhibitors of a Class II HDAC enzyme (HDAC6) and find one that retains high selectivity in macrophages.
Inhibitory effects of bisbenzylisoquinolines on synthesis of the inflammatory cytokines interleukin-1 and tumour necrosis factor-alpha
Publisher: Hindawi Limited
Date: 1993
DOI: 10.1155/S0962935193000262
Abstract: Synthesis of IL-1β and TNFα by human monocytesmacrophages was significantly inhibited by eleven bisbenzylisoquinolines and one half-molecule (benzylisoquinoline), with IC 50 values in the μM range. The results indicate that these compounds may have value in the therapy of human diseases where these inflammatory cytokines have a central role in pathogenesis.
Base-sensitivity of arginine alpha-ketoamide inhibitors of serine proteases
Publisher: CSIRO Publishing
Date: 2009
DOI: 10.1071/CH09150
Abstract: Serine protease enzymes use a serine hydroxyl group to catalyze hydrolysis of polypeptides. They are important in immunity, blood clotting, digestion, and as therapeutic or diagnostic targets for cancer, diabetes, stroke, inflammatory diseases, and viral infections. Their inhibitors typically possess an electrophile that reacts with the nucleophilic hydroxyl group of the catalytic serine. The α-ketoamide is a valuable electrophile in inhibitor discovery as it permits synthetic elaboration to both sides, unlike other electrophiles. Here we show that an α-ketoamide is unstable above pH 7 when adjacent to the C-terminus of arginine – the guanidine side chain condenses with the α-ketoamide at the keto group rather than the amide carbonyl to form a six-membered hemiaminal rather than a seven-membered lactam.
Profiling Gene Expression Induced by Protease-Activated Receptor 2 (PAR2) Activation in Human Kidney Cells
Publisher: Public Library of Science (PLoS)
Date: 02-11-2010
Structure of West Nile Virus NS3 Protease: Ligand Stabilization of the Catalytic Conformation
Publisher: Elsevier BV
Date: 02-2009
DOI: 10.1016/J.JMB.2008.11.026
Abstract: Over the last decade, West Nile virus has spread rapidly via mosquito transmission from infected migratory birds to humans. One potential therapeutic approach to treating infection is to inhibit the virally encoded serine protease that is essential for viral replication. Here we report the crystal structure of the viral NS3 protease tethered to its essential NS2B cofactor and bound to a potent substrate-based tripeptide inhibitor, 2-naphthoyl-Lys-Lys-Arg-H (K(i)=41 nM), capped at the N-terminus by 2-naphthoyl and capped at the C-terminus by aldehyde. An important and unexpected feature of this structure is the presence of two conformations of the catalytic histidine suggesting a role for ligand stabilization of the catalytically competent His conformation. Analysis of other West Nile virus NS3 protease structures and related serine proteases supports this hypothesis, suggesting that the common catalytic mechanism involves an induced-fit mechanism.
Simultaneous uncoupled expression and purification of the Dengue virus NS3 protease and NS2B co-factor domain
Publisher: Elsevier BV
Date: 03-2016
DOI: 10.1016/J.PEP.2015.11.022
Abstract: Dengue Virus (DENV) infection is responsible for the world's most significant insect-borne viral disease. Despite an increasing global impact, there are neither prophylactic nor therapeutic options available for the effective treatment of DENV infection. An attractive target for antiviral drugs is the virally encoded trypsin-like serine protease (NS3pro) and its associated cofactor (NS2B). The NS2B-NS3pro complex is responsible for cleaving the viral polyprotein into separate functional viral proteins, and is therefore essential for replication. Recombinant expression of an active NS2B-NS3 protease has primarily been based on constructs linking the C-terminus of the approximately 40 amino acid hydrophilic cofactor domain of NS2B to the N-terminus of NS3pro via a flexible glycine linker. The resulting complex can be expressed in high yield, is soluble and catalytically active and has been used for most in vitro screening, inhibitor, and X-ray crystallographic studies over the last 15 years. Despite extensive analysis, no inhibitor drug candidates have been identified yet. Moreover, the effect of the artificial linker introduced between the protease and its cofactor is unknown. Two alternate methods for bacterial expression of non-covalently linked, catalytically active, NS2B-NS3pro complex are described here along with a comparison of the kinetics of substrate proteolysis and binding affinities of substrate-based aldehyde inhibitors. Both expression methods produced high yields of soluble protein with improved substrate proteolysis kinetics and inhibitor binding compared to their glycine-linked equivalent. The non-covalent association between NS2B and NS3pro is predicted to be more relevant for examining inhibitors that target cofactor-protease interactions rather than the protease active site. Furthermore, these approaches offer alternative strategies for the high yield co-expression of other protein assemblies.
Structure-activity relationships for macrocyclic peptidomimetic inhibitors of HIV-1 protease.
Publisher: Elsevier BV
Date: 11-1996
Self-condensation of a thiazole-peptide bearing a 21-membered loop into a library of giant macrocycles with multiple orthogonal loops
Publisher: American Chemical Society (ACS)
Date: 15-02-2006
DOI: 10.1021/OL052842E
Abstract: [reaction: see text] Tetrapeptide analogue H-[Glu-Ser-Lys(Thz)]-OH, containing a turn-inducing thiazole constraint, was used as a template to produce a 21-membered structurally characterized loop by linking Glu and Lys side chains with a Val-Ile dipeptide. This template was oligomerized in one pot to a library (cyclo-[1](n)(), n = 2-10) of giant symmetrical macrocycles (up to 120-membered rings), fused to 2-10 appended loops that were carried intact through multiple oligomerization (chain extension) and cyclization (chain terminating) reactions of the template. A three-dimensional solution structure for cyclo-[1](3) shows all three appended loops projecting from the same face of the macrocycle. This is a promising approach to separating peptide motifs over large distances.
Clean or dirty just how selective do drugs need to be?
Publisher: CSIRO Publishing
Date: 2008
DOI: 10.1071/CH08186
Abstract: Chemotherapy has developed largely on the basis of searching for chemicals with selective toxicity, targeting a specific step or receptor in a disease process without negatively impacting on normal physiology. The desire for ‘clean’ drugs that act on a single target and thus avoid side effects has led to ever-increasing timeframes for introducing new drugs to humans. This has led to reappraisal of how selective drugs need to be. Ex les here of compounds from common drug classes (kinase inhibitors, protease inhibitors, G protein coupled receptors ligands, non-steroidal anti-inflammatory drugs, statins, antibodies) highlight current debate on the merits of target selectivity versus target promiscuity in the development of drugs for inflammation, cancer, cardiovascular, central nervous system and infectious diseases.
Novel Agonists and Antagonists for Human Protease Activated Receptor 2
Publisher: American Chemical Society (ACS)
Date: 28-09-2010
DOI: 10.1021/JM100984Y
Abstract: Human protease activated receptor 2 (PAR2) is a G protein-coupled receptor that is associated with inflammatory diseases and cancers. PAR2 is activated by serine proteases that cleave its N-terminus and by synthetic peptides corresponding to the new N-terminus. Peptide agonists are widely used to characterize physiological roles for PAR2 but typically have low potency (e.g., SLIGKV-NH(2), SLIGRL-NH(2)), uncertain target selectivity, and poor bioavailability, limiting their usefulness for specifically interrogating PAR2 in vivo. Structure-activity relationships were used to derive new PAR2 agonists and antagonists containing nonpeptidic moieties. Agonist GB110 (19, EC(50) 0.28 μM) selectively induced PAR2-, but not PAR1-, mediated intracellular Ca(2+) release in HT29 human colorectal carcinoma cells. Antagonist GB83 (36, IC(50) 2 μM) is the first compound at micromolar concentrations to reversibly inhibit PAR2 activation by both proteases and other PAR2 agonists (e.g., trypsin, 2f-furoyl-LIGRLO-NH(2), 19). The new compounds are selective for PAR2 over PAR1, serum stable, and suitable for modulating PAR2 in disease models.
Low-Molecular-Weight Peptidic and Cyclic Antagonists of the Receptor for the Complement Factor C5a
Publisher: American Chemical Society (ACS)
Date: 07-05-1999
DOI: 10.1021/JM9806594
Three Homology Models of PAR2 Derived from Different Templates: Application to Antagonist Discovery
Publisher: American Chemical Society (ACS)
Date: 22-05-2015
Abstract: Protease activated receptor 2 (PAR2) is an unusual G-protein coupled receptor (GPCR) involved in inflammation and metabolism. It is activated through cleavage of its N-terminus by proteases. The new N-terminus functions as a tethered ligand that folds back and intramolecularly activates PAR2, initiating multiple downstream signaling pathways. The only compounds reported to date to inhibit PAR2 activation are of moderate potency. Three structural models for PAR2 have been constructed based on sequence homology with known crystal structures for bovine rhodopsin, human ORL-1 (also called nociceptin/orphanin FQ receptor), and human PAR1. The three PAR2 model structures were compared and used to predict potential interactions with ligands. Virtual screening for ligands using the Chembridge database, and either ORL-1 or PAR1 derived PAR2 models led to identification of eight new small molecule PAR2 antagonists (IC50 10-100 μM). Notably, the most potent compound 1 (IC50 11 μM) was derived from the less homologous template protein, human ORL-1. The results suggest that virtual screening against multiple homology models of the same GPCR can produce structurally erse antagonists and that this may be desirable even when some models have less sequence homology with the target protein.
A general synthetic route to pentaamminecobalt(III) complexes of N-bonded amides, ureas, carbamates, sulfinamides, sulfonamides and sulfamate
Publisher: Elsevier BV
Date: 09-1990
Conformationally homogeneous cyclic tetrapeptides: Useful new three-dimensional scaffolds
Publisher: American Chemical Society (ACS)
Date: 18-12-2003
DOI: 10.1021/JA029205T
Abstract: The most commonly recognized motifs in protein-protein interactions are gamma and beta turns, which are defined by three to four contiguous amino acids in a peptide sequence. Cyclic tetrapeptides thus represent minimalist turn mimetics, but their usefulness is compromised by strain in their 12-membered rings, making them difficult to cyclize, unstable to hydrolysis/metabolism, and conformationally heterogeneous in polar solvents. Appropriate placement of a beta amino acid in a tetrapeptide creates a 13-membered ring that is shown to be easier to cyclize, hydrolytically more stable, and conformationally homogeneous in polar solvents such as DMSO and water. Three-dimensional structures reveal that these cyclic tetrapeptides are novel rigid scaffolds, their unique side-chain projections matching a structurally erse range of useful nonpeptidic templates, including sugars and spirocyclic compounds, found as components of natural products. The results provide a potentially useful link between protein architecture and organic natural products. On the basis of protein turn sequences (not protein structures) alone simple cyclic tetrapeptide libraries with a beta amino acid can be rationally designed as conformationally restricted, easily synthesized, and stereochemically controlled screening tools for rapidly identifying pharmacophore space that can then be computer-matched to more complex known natural product templates for drug development.
Amyloid Formation from an α‐Helix Peptide Bundle Is Seeded by 310‐Helix Aggregates
Publisher: Wiley
Date: 15-12-2010
Abstract: Transformation of proteins and peptides to fibrillar aggregates rich in β sheets underlies many diseases, but mechanistic details of these structural transitions are poorly understood. To simulate aggregation, four equivalents of a water-soluble, α-helical (65 %) hipathic peptide (AEQLLQEAEQLLQEL) were assembled in parallel on an oxazole-containing macrocyclic scaffold. The resulting 4α-helix bundle is monomeric and even more α helical (85 %), but it is also unstable at pH 4 and undergoes concentration-dependent conversion to β-sheet aggregates and amyloid fibrils. Fibrils twist and grow with time, remaining flexible like rope (>1 μm long, 5-50 nm wide) with multiple strings (2 nm), before ageing to matted fibers. At pH 7 the fibrils revert back to soluble monomeric 4α-helix bundles. During α→β folding we were able to detect soluble 3(10) helices in solution by using 2D-NMR, CD and FTIR spectroscopy. This intermediate satisfies the need for peptide elongation, from the compressed α helix to the fully extended β strand/sheet, and is driven here by 3(10) -helix aggregation triggered in this case by template-promoted helical bundling and by hydrogen-bonding glutamic acid side chains. A mechanism involving α⇌α(4) ⇌(3(10) )(4) ⇌(3(10) )(n) ⇌(β)(n) ⇋m(β)(n) equilibria is plausible for this peptide and also for peptides lacking hydrogen-bonding side chains, with unfavourable equilibria slowing the α→β conversion.
β-strand mimicking macrocyclic amino acids: Templates for protease inhibitors with antiviral activity
Publisher: American Chemical Society (ACS)
Date: 12-12-2002
DOI: 10.1021/JM010414I
Abstract: New amino acids are reported in which component macrocycles are constrained to mimic tripeptides locked in a beta-strand conformation. The novel amino acids involve macrocycles functionalized with both an N- and a C-terminus enabling addition of appendages at either end to modify receptor affinity, selectivity, or membrane permeability. We show that the cycles herein are effective templates within inhibitors of HIV-1 protease. Eleven compounds originating from such bifunctionalized cyclic templates are potent inhibitors of HIV-1 protease (Ki 0.3-50 nM pH 6.5, I = 0.1 M). Unlike normal peptides comprising amino acids, five of these macrocycle-containing compounds are potent antiviral agents with sub-micromolar potencies (IC(50) 170-900 nM) against HIV-1 replication in human MT2 cells. The most active antiviral agents are the most lipophilic, with calculated values of LogD(6.5) > or = 4. All molecules have a conformationally constrained 17-membered macrocyclic ring that has been shown to structurally mimic a tripeptide segment (Xaa)-(Val/Ile)-(Phe/Tyr) of a peptide substrate in the extended conformation. The presence of two trans amide bonds and a para-substituted aromatic ring prevents intramolecular hydrogen bonds and fixes the macrocycle in the extended conformation. Similarly constrained macrocycles may be useful templates for the creation of inhibitors for the many other proteins and proteases that recognize peptide beta-strands.
Achiral Derivatives of Hydroxamate AR-42 Potently Inhibit Class I HDAC Enzymes and Cancer Cell Proliferation
Publisher: American Chemical Society (ACS)
Date: 08-05-2020
Alpha Helix Nucleation by a Simple Cyclic Tetrapeptide
Publisher: CSIRO Publishing
Date: 2017
DOI: 10.1071/CH16591
Abstract: The simple cyclic tetrapeptide cyclo-(1,4)-[Ala-Arg-Ala-homoGlu]-NH2 (3) is shown to adopt an unusual α-turn structure, which is not α-helical but can nucleate α-helicity when attached to the N-terminus of either model peptides or two biologically relevant peptides. This new N-terminal helix-capping macrocycle provides very simple and rapid synthetic access to α-helical peptide structures.
Stereoelectronic Effects on Dienophile Separation Influence the Diels–Alder Synthesis of Molecular Clefts
Publisher: Figshare
Date: 2019
Peptide inhibitors of the Escherichia coli DsbA oxidative machinery essential for bacterial virulence
Publisher: American Chemical Society (ACS)
Date: 18-12-2015
DOI: 10.1021/JM500955S
Abstract: One approach to address antibiotic resistance is to develop drugs that interfere with bacterial virulence. A master regulator of virulence in Gram-negative bacteria is the oxidative folding machinery comprising DsbA and DsbB. A crystal structure at 2.5 Å resolution is reported here for Escherichia coli DsbA complexed with PFATCDS, a heptapeptide derived from the partner protein Escherichia coli DsbB. Details of the peptide binding mode and binding site provide valuable clues for inhibitor design. Structure-activity relationships for 30 analogues were used to produce short peptides with a cysteine that bind tightly to EcDsbA (Kd = 2.0 ± 0.3 μM) and inhibit its activity (IC50 = 5.1 ± 1.1 μM). The most potent inhibitor does not bind to or inhibit human thioredoxin that shares a similar active site. This finding suggests that small molecule inhibitors can be designed to exploit a key interaction of EcDsbA, as the basis for antivirulence agents with a novel mechanism of action.
Solution structures in aqueous SDS micelles of two amyloid β peptides of aβ(1-28) mutated at the α-secretase cleavage site (K16E, K16F)
Publisher: Elsevier BV
Date: 06-2000
Lipopolysaccharide promotes Drp1‐dependent mitochondrial fission and associated inflammatory responses in macrophages
Publisher: Wiley
Date: 20-07-2020
DOI: 10.1111/IMCB.12363
Helix-Constrained Nociceptin Peptides Are Potent Agonists and Antagonists of ORL-1 and Nociception
Publisher: Elsevier
Date: 2015
DOI: 10.1016/BS.VH.2014.10.001
Abstract: Nociceptin (orphanin FQ) is a 17-residue neuropeptide hormone with roles in both nociception and analgesia. It is an opioid-like peptide that binds to and activates the G-protein-coupled receptor opioid receptor-like-1 (ORL-1, NOP, orphanin FQ receptor, kappa-type 3 opioid receptor) on central and peripheral nervous tissue, without activating classic delta-, kappa-, or mu-opioid receptors or being inhibited by the classic opioid antagonist naloxone. The three-dimensional structure of ORL-1 was recently published, and the activation mechanism is believed to involve capture by ORL-1 of the high-affinity binding, prohelical C-terminus. This likely anchors the receptor-activating N-terminus of nociception nearby for insertion in the membrane-spanning helices of ORL-1. In search of higher agonist potency, two lysine and two aspartate residues were strategically incorporated into the receptor-binding C-terminus of the nociceptin sequence and two Lys(i)→Asp(i+4) side chain-side chain condensations were used to generate lactam cross-links that constrained nociceptin into a highly stable α-helix in water. A cell-based assay was developed using natively expressed ORL-1 receptors on mouse neuroblastoma cells to measure phosphorylated ERK as a reporter of agonist-induced receptor activation and intracellular signaling. Agonist activity was increased up to 20-fold over native nociceptin using a combination of this helix-inducing strategy and other amino acid modifications. An NMR-derived three-dimensional solution structure is described for a potent ORL-1 agonist derived from nociceptin, along with structure-activity relationships leading to the most potent known α-helical ORL-1 agonist (EC₅₀ 40 pM, pERK, Neuro-2a cells) and antagonist (IC₅₀ 7 nM, pERK, Neuro-2a cells). These α-helix-constrained mimetics of nociceptin(1-17) had enhanced serum stability relative to unconstrained peptide analogues and nociceptin itself, were not cytotoxic, and displayed potent thermal analgesic and antianalgesic properties in rats (ED₅₀ 70 pmol, IC₅₀ 10 nmol, s.c.), suggesting promising uses in vivo for the treatment of pain and other ORL-1-mediated responses.
Towards Arginine Mimetics
Publisher: Figshare
Date: 2019
Functional Heterogeneity and Antimycobacterial Effects of Mouse Mucosal-Associated Invariant T Cells Specific for Riboflavin Metabolites
Publisher: The American Association of Immunologists
Date: 15-07-2015
Abstract: Mucosal-associated invariant T (MAIT) cells have a semi-invariant TCR Vα-chain, and their optimal development is dependent upon commensal flora and expression of the nonpolymorphic MHC class I–like molecule MR1. MAIT cells are activated in an MR1-restricted manner by erse strains of bacteria and yeast, suggesting a widely shared Ag. Recently, human and mouse MR1 were found to bind bacterial riboflavin metabolites (ribityllumazine [RL] Ags) capable of activating MAIT cells. In this study, we used MR1/RL tetramers to study MR1 dependency, subset heterogeneity, and protective effector functions important for tuberculosis immunity. Although tetramer+ cells were detected in both MR1+/+ and MR1−/− TCR Vα19i-transgenic (Tg) mice, MR1 expression resulted in significantly increased tetramer+ cells coexpressing TCR Vβ6/8, NK1.1, CD44, and CD69 that displayed more robust in vitro responses to IL-12 plus IL-18 and RL Ag, indicating that MR1 is necessary for the optimal development of the classic murine MAIT cell memory/effector subset. In addition, tetramer+ MAIT cells expressing CD4, CD8, or neither developing in MR1+/+ Vα19i-Tg mice had disparate cytokine profiles in response to RL Ag. Therefore, murine MAIT cells are considerably more heterogeneous than previously thought. Most notably, after mycobacterial pulmonary infection, heterogeneous subsets of tetramer+ Vα19i-Tg MAIT cells expressing CXCR3 and α4β1 were recruited into the lungs and afforded early protection. In addition, Vα19iCα−/−MR+/+ mice were significantly better protected than were Vα19iCα−/−MR1−/−, wild-type, and MR1−/− non-Tg mice. Overall, we demonstrate considerable functional ersity of MAIT cell responses, as well as that MR1-restricted MAIT cells are important for tuberculosis protective immunity.
NMR solution structure of the RNA-binding peptide from human immunodeficiency virus (type 1) Rev
Publisher: American Chemical Society (ACS)
Date: 04-07-1995
DOI: 10.1021/BI00026A005
Abstract: NMR spectroscopy has been used to solve the three-dimensional solution structure of a minimal RNA-binding domain of the Rev protein from the human immunodeficiency virus (type 1), an essential regulatory protein for viral replication. The presence of 10 arginine residues in the 17-residue peptide Rev34-50 caused significant problems in assignment of the NMR spectra. To improve spectral resolution, the peptide was synthesized with an alanine replacing a nonessential arginine and with selectively 15N-labeled residues. Contrary to Chou-Fasman modeling predictions an alpha-helix was detected in both water and 20% trifluoroethanol (TFE) and was found to span residues that constitute the RNA-binding and nuclear-localizing domains of Rev. The sequence-specific information provided by the NMR data gives a full description of the solution conformation of Rev34-50 which serves as a template for investigating binding of the peptide to RNA from the Rev response element (RRE). Preliminary modeling suggests that the helix can fit neatly into the expanded major groove of the RRE where interactions between the peptide side chains and the RNA can be identified. These data may aid the construction of a suitable pharmacophore model for the rational design of molecules that block Rev-RNA binding and inhibit HIV replication.
Antiarthritic activity of an orally active C5a receptor antagonist against antigen-induced monarticular arthritis in the rat
Publisher: Wiley
Date: 09-2002
DOI: 10.1002/ART.10449
Abstract: To determine if the new, orally active C5a receptor antagonist, the cyclic peptide AcF-[OPdChaWR], reduces the severity of pathology in a rat model of immune-mediated monarticular arthritis. Arthritis was induced in the right knee of previously sensitized rats by the intraarticular injection of methylated bovine serum albumin. Rats were examined for either 14 days or 28 days, or for 49 days following a second antigen challenge at 28 days. The C5a antagonist (1 or 3 mg/kg/day) and/or ibuprofen (30 mg/kg/day) were administered orally on a daily basis either before or after arthritis induction. Rats receiving AcF-[OPdChaWR] had significant reductions in right knee swelling, gait disturbance, lavaged joint cell numbers, and right knee histopathology, as well as in serum levels of tumor necrosis factor alpha (TNFalpha) and intraarticular levels of interleukin-6 and TNFalpha on day 14. In the 14- and 28-day studies, ibuprofen resulted in a similar reduction in gait abnormalities and intraarticular inflammatory cells compared with the C5a antagonist, but was less effective in reducing knee swelling over the course of the study and had no effect on knee histopathology. Combination therapy with AcF-[OPdChaWR] and ibuprofen resulted in no greater efficacy than with the C5a antagonist alone. Rats injected twice with the antigen in the 49-day study displayed the most severe histopathology and this, as well as knee swelling and gait abnormalities, was significantly reduced by repeated treatment with the C5a antagonist. An agent that inhibits the action of C5a in this model significantly reduced joint pathology, while ibuprofen was not effective. C5a antagonists could therefore have broader therapeutic benefits than nonsteroidal antiinflammatory drugs as antiarthritic agents for rheumatoid arthritis.
Folding pentapeptides into left and right handed alpha helices
Publisher: Elsevier BV
Date: 06-2012
Histone deacetylase inhibitors as suppressors of bone destruction in inflammatory diseases
Publisher: Oxford University Press (OUP)
Date: 16-12-2011
DOI: 10.1111/J.2042-7158.2011.01421.X
Abstract: Despite progress in developing many new anti-inflammatory treatments in the last decade, there has been little progress in finding treatments for bone loss associated with inflammatory diseases, such as rheumatoid arthritis and periodontitis. For instance, treatment of rheumatic diseases with anti-tumour necrosis factor-alpha agents has been largely successful in reducing inflammation, but there have been varying reports regarding its effectiveness at inhibiting bone loss. In addition, there is often a delay in finding the appropriate anti-inflammatory therapy for in idual patients, and some therapies, such as disease modifying drugs, take time to have an effect. In order to protect the bone, adjunct therapies targeting bone resorption are being developed. This review focuses on new treatments based on using histone deacetylase inhibitors (HDACi) to suppress bone loss in these chronic inflammatory diseases. A number of selected HDACi have been shown to suppress bone resorption by osteoclasts in vitro and in animal models of chronic inflammatory diseases. Recent reports indicate that these small molecules, which can be administered orally, could protect the bone and might be used in combination with current anti-inflammatory treatments. HDACi do have potential to suppress bone destruction in chronic inflammatory diseases including periodontitis and rheumatoid arthritis.
Left- and right-handed alpha-helical turns in homo- and hetero-chiral helical scaffolds
Publisher: American Chemical Society (ACS)
Date: 06-10-2009
DOI: 10.1021/JA9065283
Abstract: Proteins typically consist of right-handed alpha helices, whereas left-handed alpha helices are rare in nature. Peptides of 20 amino acids or less corresponding to protein helices do not form thermodynamically stable alpha helices in water away from protein environments. The smallest known water-stable right- (alpha(R)) and left- (alpha(L)) handed alpha helices are reported, each stabilized in cyclic pentapeptide units containing all L- or all D-amino acids. Homochiral decapeptides comprising two identical cyclic pentapeptides (alpha(R)alpha(R) or alpha(L)alpha(L)) are continuous alpha-helical structures that are extremely stable to denaturants, degradative proteases, serum, and additives like TFE, acid, and base. Heterochiral decapeptides comprising two different cyclic pentapeptides (alpha(L)alpha(R) or alpha(R)alpha(L)) maintain the respective helical handedness of each monocyclic helical turn component but adopt extended or bent helical structures depending on the solvent environment. Adding TFE to their aqueous solutions caused a change to bent helical structures with slightly distorted N-terminal alpha(R) or alpha(L)-helical turns terminated by a Schellman-like motif adjacent to the C-terminal alpha(L) or alpha(R)-turn. This hinge-like switching between structures in response to an external cue suggests possible uses in larger structures to generate smart materials. The library of left- and right-handed 1-3 turn alpha-helical compounds reported herein project their amino acid side chains into very different regions of 3D space, constituting a unique and potentially valuable class of novel scaffolds.
Europium-Labeled Synthetic C3a Protein as a Novel Fluorescent Probe for Human Complement C3a Receptor
Publisher: American Chemical Society (ACS)
Date: 31-05-2017
DOI: 10.1021/ACS.BIOCONJCHEM.7B00132
Abstract: Measuring ligand affinity for a G protein-coupled receptor is often a crucial step in drug discovery. It has been traditionally determined by binding putative new ligands in competition with native ligand labeled with a radioisotope of finite lifetime. Competing instead with a lanthanide-based fluorescent ligand is more attractive due to greater longevity, stability, and safety. Here, we have chemically synthesized the 77 residue human C3a protein and conjugated its N-terminus to europium diethylenetriaminepentaacetate to produce a novel fluorescent protein (Eu-DTPA-hC3a). Time-resolved fluorescence analysis has demonstrated that Eu-DTPA-hC3a binds selectively to its cognate G protein-coupled receptor C3aR with full agonist activity and similar potency and selectivity as native C3a in inducing calcium mobilization and phosphorylation of extracellular signal-regulated kinases in HEK293 cells that stably expressed C3aR. Time-resolved fluorescence analysis for saturation and competitive binding gave a dissociation constant (K
Activation of protease‐activated receptor 2 is associated with blood pressure regulation and proteinuria reduction in metabolic syndrome
Publisher: Wiley
Date: 21-11-2020
Abstract: Metabolic syndrome (MetS) increases the risk of kidney disease. In SHRSP.Z-Lepr
Catalyst‐Free N‐Arylation Using Unactivated Fluorobenzenes
Publisher: Wiley
Date: 02-07-2012
Potent Heterocyclic Ligands for Human Complement C3a Receptor
Publisher: American Chemical Society (ACS)
Date: 08-10-2014
DOI: 10.1021/JM500956P
Abstract: The G-protein coupled receptor (C3aR) for human inflammatory protein complement C3a is an important component of immune, inflammatory, and metabolic diseases. A flexible compound (N2-[(2,2-diphenylethoxy)acetyl]-l-arginine, 4), known as a weak C3aR antagonist (IC50 μM), was transformed here into potent agonists (EC50 nM) of human macrophages (Ca(2+) release in HMDM) by incorporating aromatic heterocycles. Antagonists were also identified. A linear correlation between binding affinity for C3aR and calculated hydrogen-bond interaction energy of the heteroatom indicated that its hydrogen-bonding capacity influenced ligand affinity and function mediated by C3aR. Hydrogen-bond accepting heterocycles (e.g., imidazole) conferred the highest affinity and agonist potency (e.g., 21, EC50 24 nM, Ca(2+), HMDM) with comparable efficacy and immunostimulatory activity as that of C3a in activating human macrophages (Ca(2+), IL1β, TNFα, CCL3). These potent and selective modulators of C3aR, inactivated by a C3aR antagonist, are stable C3a surrogates for interrogating roles for C3aR in physiology and disease.
Unexpected photolytic decomposition of alkyl azides under mild conditions
Publisher: Royal Society of Chemistry (RSC)
Date: 2007
DOI: 10.1039/B708134K
Abstract: Alkyl azides have been found to undergo an unexpectedly facile photodecomposition under mild conditions (laboratory light) and the reaction gives rise to small amounts of aldehydes and monoacyl aminal rearrangement products that can dramatically impact on the uses of azides in chemistry, biology and medicine.
Identification of brain metastasis genes and therapeutic evaluation of histone deacetylase inhibitors in a clinically relevant model of breast cancer brain metastasis
Publisher: The Company of Biologists
Date: 2018
DOI: 10.1242/DMM.034850
Abstract: Breast cancer brain metastasis remains largely incurable. While several mouse models have been developed to investigate the genes and mechanisms regulating breast cancer brain metastasis, these models often lack clinical relevance since they require the use of immune-compromised mice and/or are poorly metastatic to brain from the mammary gland. We describe the development and characterisation of an aggressive brain metastatic variant of the 4T1 syngeneic model (4T1Br4) that spontaneously metastasises to multiple organs, but is selectively more metastatic to the brain from the mammary gland than parental 4T1 tumours. By immunohistochemistry, 4T1Br4 tumours and brain metastases display a triple negative phenotype, consistent with the high propensity of this breast cancer subtype to spread to brain. In vitro assays indicate that 4T1Br4 cells have an enhanced ability to adhere to or migrate across a brain-derived endothelial monolayer and greater invasive response to brain-derived soluble factors compared to 4T1 cells. These properties are likely to contribute to the brain-selectivity of 4T1Br4 tumours. Expression profiling and gene set enrichment analyses demonstrate the clinical relevance of the 4T1Br4 model at the transcriptomic level. Pathway analyses implicate tumour-intrinsic immune regulation and vascular interactions in successful brain colonisation, revealing potential therapeutic targets. Evaluation of two histone deacetylase inhibitors, SB939 and 1179.4b, shows partial efficacy against 4T1Br4 metastasis to brain and other sites in vivo and potent radio-sensitising properties in vitro. The 4T1Br4 model provides a clinically relevant tool for mechanistic studies and to evaluate novel therapies against brain metastasis.
Protective effect of a new C5a receptor antagonist against ischemia-reperfusion injury in the rat small intestine
Publisher: Elsevier BV
Date: 04-2002
Modifying a Hydroxyl Patch in Glucagon-like Peptide 1 Produces Biased Agonists with Unique Signaling Profiles
Publisher: American Chemical Society (ACS)
Date: 19-08-2022
DOI: 10.1021/ACS.JMEDCHEM.2C00653
Abstract: Glucagon-like peptide-1 (GLP-1) lowers blood glucose by inducing insulin but also has other poorly understood properties. Here, we show that hydroxy amino acids (Thr11, Ser14, Ser17, Ser18) in GLP-1(7-36) act in concert to direct cell signaling. Mutating any single residue to alanine removes one hydroxyl group, thereby reducing receptor affinity and cAMP 10-fold, with Ala11 or Ala14 also reducing β-arrestin-2 10-fold, while Ala17 or Ala18 also increases ERK1/2 phosphorylation 5-fold. Multiple alanine mutations more profoundly bias signaling, differentially silencing or restoring one or more signaling properties. Mutating three serines silences only ERK1/2, the first ex le of such bias. Mutating all four residues silences β-arrestin-2, ERK1/2, and Ca
Tuning Electrostatic and Hydrophobic Surfaces of Aromatic Rings to Enhance Membrane Association and Cell Uptake of Peptides
Publisher: Wiley
Date: 26-05-2022
Abstract: Aromatic groups are key mediators of protein–membrane association at cell surfaces, contributing to hydrophobic effects and π‐membrane interactions. Here we show electrostatic and hydrophobic influences of aromatic ring substituents on membrane affinity and cell uptake of helical, cyclic and cell penetrating peptides. Hydrophobicity is important, but subtle changes in electrostatic surface potential, dipoles and polarizability also enhance association with phospholipid membranes and cell uptake. A combination of fluorine and sulfur substituents on an aromatic ring induces microdipoles that enhance cell uptake of 12‐residue peptide inhibitors of p53‐HDM2 interaction and of cell‐penetrating cyclic peptides. These aromatic motifs can be readily inserted into peptide sidechains to enhance their cell uptake.
Inhibition of C5a-induced neutrophil chemotaxis and macrophage cytokine production in vitro by a new C5a receptor antagonist
Publisher: Elsevier BV
Date: 09-2000
DOI: 10.1016/S0006-2952(00)00361-0
Abstract: A cyclic peptide, Phe-[Orn-Pro-D-Cyclohexylalanine-Trp-Arg] (F-[OPdChaWR]), was recently shown in vitro to antagonise the binding of C5a to its receptor (CD88) on human polymorphonuclear leukocytes (PMNs) and in vivo to inhibit the neutropenia associated with septic shock induced by lipopolysaccharide (LPS) in rats. The aim of this study was to investigate whether F-[OPdChaWR] inhibits C5a-mediated chemotaxis of human PMNs using a modified Boyden chamber and C5a-stimulated release of cytokines from human monocytes in vitro. Approximately 50% of the chemotactic activity induced by 10 nM C5a was inhibited by 76 nM F-[OPdChaWR]. This correlated with inhibition of C5a-induced polarisation of PMNs by F-[OPdChaWR]. C5a alone failed to induce release of the inflammatory cytokines interleukin(IL)-1beta, tumour necrosis factor (TNF)-alpha, and IL-6 from human monocytes at concentrations up to 100 nM. However, in the presence of low concentrations of LPS (50 ng/mL), both IL-1beta and TNF-alpha were stimulated by 1 nM C5a. This co-stimulation was inhibited by F-[OPdChaWR] with IC(50)s of 0.8 and 6.9 nM for release of TNF-alpha and IL-1beta, respectively. No agonist activity was detected for F-[OPdChaWR] in either the chemotaxis or cytokine release assays at concentrations up to 50 microM. These results show that F-[OPdChaWR] inhibits several important inflammatory activities of C5a and suggest that C5a receptor antagonists may be effective in the treatment of inflammatory diseases mediated by C5a.
Recent Advances in β-Strand Mimetics
Publisher: Wiley
Date: 18-03-2011
Reversible linkage isomerization of pentaamminecobalt(III) complexes of urea and its N-methyl derivatives
Publisher: Elsevier BV
Date: 10-1988
Targeting HIV-1 protease: A test of drug-design methodologies
Publisher: Elsevier BV
Date: 02-1995
DOI: 10.1016/S0165-6147(00)88980-4
Abstract: The proteinase of the human immunodeficiency virus (HIV-1 protease) is an obvious ex le of a receptor for which drug design methodologies have been successfully applied. In this article, Michael West and David Fairlie outline the specific progress made to date towards the rational design of protease inhibitors as anti-HIV drugs, and compare their pharmacological profiles. The rationale employed in designing protease inhibitors illustrates evolving trends in drug design, problems in comparing assay data, and obstacles to developing enzyme inhibitors into drugs.
Mucosal-Associated Invariant T Cells Augment Immunopathology and Gastritis in Chronic Helicobacter pylori Infection
Publisher: The American Association of Immunologists
Date: 03-2018
Abstract: Mucosal-associated invariant T (MAIT) cells produce inflammatory cytokines and cytotoxic granzymes in response to by-products of microbial riboflavin synthesis. Although MAIT cells are protective against some pathogens, we reasoned that they might contribute to pathology in chronic bacterial infection. We observed MAIT cells in proximity to Helicobacter pylori bacteria in human gastric tissue, and so, using MR1-tetramers, we examined whether MAIT cells contribute to chronic gastritis in a mouse H. pylori SS1 infection model. Following infection, MAIT cells accumulated to high numbers in the gastric mucosa of wild-type C57BL/6 mice, and this was even more pronounced in MAIT TCR transgenic mice or in C57BL/6 mice where MAIT cells were preprimed by Ag exposure or prior infection. Gastric MAIT cells possessed an effector memory Tc1/Tc17 phenotype, and were associated with accelerated gastritis characterized by augmented recruitment of neutrophils, macrophages, dendritic cells, eosinophils, and non-MAIT T cells and by marked gastric atrophy. Similarly treated MR1−/− mice, which lack MAIT cells, showed significantly less gastric pathology. Thus, we demonstrate the pathogenic potential of MAIT cells in Helicobacter-associated immunopathology, with implications for other chronic bacterial infections.
Cycloadditions of isobenzofuran to a constrained template bearing neighboring dienophiles
Publisher: Wiley
Date: 05-05-2003
Abstract: A high yielding synthesis of the pentacyclic diene-dione 1 has enabled investigation of its reactivity as a double dienophile in Diels-Alder [4+2] cycloadditions with isobenzofuran, leading to novel and highly symmetrical three-sided cavitands 3 and 4.
Tolyporphin Macrocycles from the Cyanobacterium Tolypothrix nodosa Selectively Bind Copper and Silver and Reverse Multidrug Resistance.
Publisher: American Chemical Society (ACS)
Date: 27-02-2017
DOI: 10.1021/ACS.INORGCHEM.6B03000
Abstract: Tolyporphins are glycosylated macrocycles isolated from lipophilic soil extracts of the cyanobacterium, Tolypothrix nodosa, and found to potentiate the cytotoxicity of antitumor drugs like vinblastine and adriamycin. Here we find that, unlike porphyrins, tolyporphins are not able to form complexes with most metal ions. However, they do react strongly with copper(II) and silver(II), forming square-planar metal complexes with an unpaired electron in a d
Anti-Inflammatory activity of a holothurian (sea cucumber) food supplement in rats
Publisher: Springer Science and Business Media LLC
Date: 12-1994
DOI: 10.1007/BF02678607
Non-peptidic anti-aids agents: Inhibition of HIV-1 proteinase by disulfonates
Publisher: Elsevier BV
Date: 10-1992
DOI: 10.1016/0006-291X(92)91102-V
Abstract: Based upon an earlier observation that sodium docosanedioate (NaO2C-(CH2)20-CO2NA) weakly inhibits HIV-1 proteinase (IC50 12 microM), we have identified a class of more potent inhibitors (sulfonic acids) of this enzyme which are likewise dianionic at pH 5-6.5. Many of the compounds were moderately strong inhibitors of the enzyme (IC50 40nM-10 microM) and some have previously been shown to have anti-HIV activity in lymphocytes. Proteinase inhibition was dependent on the separation between sulfonate/carboxylate substituents, consistent with the hypothesis that negative charged ends of an inhibitor might form ionic bonds with Arg 8 and Arg 108 located at either end of the substrate-binding groove of the enzyme. The binding mode remains to be established by structure elucidation. Results for enzyme inhibition are presented along with structure-activity relationships and evidence for pH dependent inhibition. The general observations reported here may be useful for developing more potent and selective non-peptidic proteinase inhibitors.
Update 1 of: Beta-Strand Mimetics
Publisher: American Chemical Society (ACS)
Date: 09-06-2010
DOI: 10.1021/CR900395Y
IL-23 costimulates antigen-specific MAIT cell activation and enables vaccination against bacterial infection
Publisher: American Association for the Advancement of Science (AAAS)
Date: 11-2019
DOI: 10.1126/SCIIMMUNOL.AAW0402
Abstract: ICOS- and IL-23–mediated costimulation are important for driving in vivo activation of antigen-specific MAIT cells.
Protease activated receptor 2 (PAR2) modulators: a patent review (2010–2015)
Publisher: Informa UK Limited
Date: 03-03-2016
DOI: 10.1517/13543776.2016.1154540
Abstract: Protease activated receptor 2 (PAR2) is a self-activated G protein-coupled receptor that has been implicated in several diseases, including inflammatory, gastrointestinal, respiratory, metabolic diseases, cancers and others, making it an important prospective drug target. No known endogenous ligands are available for PAR2, so having potent exogenous agonists and antagonists can be helpful for studying physiological functions of PAR2. This review covers agonist-, antagonist-, antibody- and pepducin-based modulators of PAR2 reported in patent applications between 2010-2015, along with their available structure-activity relationships, biological activities and potential uses for studying PAR2. In the last six years, substantial efforts were made towards developing PAR2 modulators, but most lack potency or selectivity or have poor pharmacokinetic profiles. Many PAR2 modulators were assessed by measuring Gαq protein-mediated calcium release in cells. This may be insufficient to fully characterize ligand function, since different ligands signal through PAR2 via multiple signaling pathways. It may be feasible to develop biased ligands as drugs that can selectively modulate one or more specific signaling pathways linking PAR2 to a specific diseased state. Accordingly, potent, orally bioavailable, pathway- and receptor-selective PAR2 modulators may be an achievable goal to realizing effective drugs that can treat PAR2-mediated diseases.
A potent and selective inhibitor of group IIa secretory phospholipase A(2) protects rats from TNBS-induced colitis
Publisher: Elsevier BV
Date: 05-2005
DOI: 10.1016/J.INTIMP.2005.01.003
Abstract: Secretory phospholipase A(2) (sPLA(2)) enzymes have been implicated in the pathogenesis of human inflammatory bowel disease (IBD). In this study we compared the efficacy of a potent, new and highly selective inhibitor of group IIa human sPLA(2) enzyme (5-(4-benzyloxyphenyl)-4S-(7-phenylheptanoylamino)-pentanoic acid sPLA(2)I), with that of sulfasalazine, in a rat model of trinitrobenzene sulfonic acid (TNBS)-induced colitis. Following a single oral dose of sPLA(2)I (5 mg/kg), pharmacoactive levels of drug were detected in the serum within 15 min and for up to 24 h by liquid chromatography mass spectrometry analysis. Rats treated with sPLA(2)I (5 mg/kg/day) prior to induction of colitis were significantly healthier than TNBS-alone rats, as shown by reduced mortality, improved food intake and increased body weight, and significantly reduced colon myeloperoxidase levels, edema, tumour necrosis factor-alpha levels, and colon macroscopic pathology scores after 8 days. Rats pretreated with sulfasalazine (100 mg/kg/day) also had reduced disease expression markers similar to the sPLA(2)I, but exhibited no improvement in colon edema. This study supports a role for the group IIa sPLA(2) enzyme in pathology associated with the TNBS rat model of IBD, and suggests a possible therapeutic application for selective inhibitors of group IIa sPLA(2) inhibitors in the treatment of IBD.
Inhibiting histone deacetylase 1 suppresses both inflammation and bone loss in arthritis
Publisher: Oxford University Press (OUP)
Date: 31-03-2015
DOI: 10.1093/RHEUMATOLOGY/KEV022
Abstract: Histone deacetylase 1 (HDAC1) is highly expressed in the synovium of RA patients. Thus we aimed to investigate a novel HDAC inhibitor (HDACi), NW-21, designed to target HDAC1. The effect of NW-21 on osteoclast formation and activity, cytokine and chemokine expression in vitro and arthritis in mice was assessed. The effects on human osteoclast formation and activity derived from human blood monocytes stimulated with receptor activator of nuclear factor κB ligand (RANKL) and M-CSF were assessed. The anti-inflammatory activity of NW-21 was assessed using human monocytes stimulated with either TNF-α or lipopolysaccharide for 24 h. mRNA expression of monocyte chemotactic protein 1 (MCP-1), TNF-α, macrophage inflammatory protein 1α (MIP-1α), IL-1 and RANTES (regulated on activation, normal T cell expressed and secreted) was assessed. The effect of NW-21 in the collagen antibody-induced arthritis model was assessed following daily oral administration at 5 mg/kg/day. The HDAC1 inhibitors NW-21 and MS-275 were compared with a broad-acting HDACi, 1179.4b. Effects on inflammation and bone were assessed using paw inflammation scoring, histology and live animal micro-CT. NW-21 suppressed osteoclast formation and activity as well as significantly reducing mRNA expression of MCP-1 and MIP-1α in monocytes stimulated by lipopolysaccharide or TNF-α (P < 0.05) in vitro. Only inhibitors that targeted HDAC1 (NW-21 and MS-275) reduced inflammation and bone loss in the arthritis model. The results indicate that inhibitors targeting HDAC1, such as NW-21 and MS-275, may be useful for treating RA, as such drugs can simultaneously target both inflammation and bone resorption.
Virtual Screening of Peptide and Peptidomimetic Fragments Targeted to Inhibit Bacterial Dithiol Oxidase DsbA
Publisher: Public Library of Science (PLoS)
Date: 30-07-2015
Enumeration, functional responses and cytotoxic capacity of MAIT cells in newly diagnosed and relapsed multiple myeloma
Publisher: Springer Science and Business Media LLC
Date: 07-03-2018
DOI: 10.1038/S41598-018-22130-1
Abstract: Mucosal-associated invariant T (MAIT) cells are T cells that recognise vitamin-B derivative Ag presented by the MHC-related-protein 1 (MR1) antigen-presenting molecule. While MAIT cells are highly abundant in humans, their role in tumour immunity remains unknown. Here we have analysed the frequency and function of MAIT cells in multiple myeloma (MM) patients. We show that MAIT cell frequency in blood is reduced compared to healthy adult donors, but comparable to elderly healthy control donors. Furthermore, there was no evidence that MAIT cells accumulated at the disease site (bone marrow) of these patients. Newly diagnosed MM patient MAIT cells had reduced IFNγ production and CD27 expression, suggesting an exhausted phenotype, although IFNγ-producing capacity is restored in relapsed/refractory patient s les. Moreover, immunomodulatory drugs Lenalidomide and Pomalidomide, indirectly inhibited MAIT cell activation. We further show that cell lines can be pulsed with vitamin-B derivative Ags and that these can be presented via MR1 to MAIT cells in vitro , to induce cytotoxic activity comparable to that of natural killer (NK) cells. Thus, MAIT cells are reduced in MM patients, which may contribute to disease in these in iduals, and moreover, MAIT cells may represent new immunotherapeutic targets for treatment of MM and other malignancies.
Mapping transmembrane residues of proteinase activated receptor 2 (PAR 2 ) that influence ligand-modulated calcium signaling
Publisher: Elsevier BV
Date: 03-2017
DOI: 10.1016/J.PHRS.2016.12.020
Abstract: Proteinase-activated receptor 2 (PAR
C5aR and C3aR antagonists each inhibit diet‐induced obesity, metabolic dysfunction, and adipocyte and macrophage signaling
Publisher: Wiley
Date: 11-2012
DOI: 10.1096/FJ.12-220582
Abstract: Mammalian survival depends on metabolizing nutrients, storing energy, and combating infection. Complement activation in blood triggers energy-depleting immune responses to fight infections. Here we identify surprising energy-conserving roles for complement proteins C5a and C3a and their receptors, C5aR and C3aR, roles that are contraindicated in complement biology. Rats fed a high-carbohydrate high-fat diet developed obesity, visceral adiposity, adipose inflammation, glucose/insulin intolerance, and cardiovascular dysfunction that correlated with increased plasma C3a, adipose C5aR, and C3aR. These in vivo changes were dramatically attenuated by receptor-selective antagonists of either C5aR (5 mg/kg/d p.o.) or C3aR (30 mg/kg/d p.o.), which both reduced proinflammatory adipokines and altered expression of inflammatory genes in adipose tissue. In vitro C5a and C3a (100 nM) exhibited novel insulin-like effects on 3T3-L1 adipocytes, promoting energy conservation by increasing glucose and fatty acid uptake while inhibiting cAMP signaling and lipolysis, and induced PGE(2) release from macrophages, effects all blocked by each respective antagonist (10 μM). These studies reveal important new links between complement signaling and metabolism, highlight new complement functions on adipocytes and in adipose tissue, demonstrate how aberrant immune responses may exacerbate obesity and metabolic dysfunction, and show that targeting C3aR or C5aR with antagonists is a new strategy for treating metabolic dysfunction.
Potent Cyclic Antagonists of the Complement C5a Receptor on Human Polymorphonuclear Leukocytes. Relationships between Structures and Activity
Publisher: American Society for Pharmacology & Experimental Therapeutics (ASPET)
Date: 25-03-2004
DOI: 10.1124/MOL.65.4.868
Helix Nucleation by the Smallest Known α‐Helix in Water
Publisher: Wiley
Date: 25-05-2016
Abstract: Cyclic pentapeptides (e.g. Ac-(cyclo-1,5)-[KAXAD]-NH2 X=Ala, 1 Arg, 2) in water adopt one α-helical turn defined by three hydrogen bonds. NMR structure analysis reveals a slight distortion from α-helicity at the C-terminal aspartate caused by torsional restraints imposed by the K(i)-D(i+4) lactam bridge. To investigate this effect on helix nucleation, the more water-soluble 2 was appended to N-, C-, or both termini of a palindromic peptide ARAARAARA (≤5 % helicity), resulting in 67, 92, or 100 % relative α-helicity, as calculated from CD spectra. From the C-terminus of peptides, 2 can nucleate at least six α-helical turns. From the N-terminus, imperfect alignment of the Asp5 backbone amide in 2 reduces helix nucleation, but is corrected by a second unit of 2 separated by 0-9 residues from the first. These cyclic peptides are extremely versatile helix nucleators that can be placed anywhere in 5-25 residue peptides, which correspond to most helix lengths in protein-protein interactions.
MAIT cells protect against pulmonary Legionella longbeachae infection
Publisher: Springer Science and Business Media LLC
Date: 22-08-2018
DOI: 10.1038/S41467-018-05202-8
Abstract: Mucosal associated invariant T (MAIT) cells recognise conserved microbial metabolites from riboflavin synthesis. Striking evolutionary conservation and pulmonary abundance implicate them in antibacterial host defence, yet their functions in protection against clinically important pathogens are unknown. Here we show that mouse Legionella longbeachae infection induces MR1-dependent MAIT cell activation and rapid pulmonary accumulation of MAIT cells associated with immune protection detectable in immunocompetent host animals. MAIT cell protection is more evident in mice lacking CD4 + cells, and adoptive transfer of MAIT cells rescues immunodeficient Rag2 −/− γC −/− mice from lethal Legionella infection. Protection is dependent on MR1, IFN-γ and GM-CSF, but not IL-17A, TNF or perforin, and enhanced protection is detected earlier after infection of mice antigen-primed to boost MAIT cell numbers before infection. Our findings define a function for MAIT cells in protection against a major human pathogen and indicate a potential role for vaccination to enhance MAIT cell immunity.
Repurposing Registered Drugs as Antagonists for Protease-Activated Receptor 2
Publisher: American Chemical Society (ACS)
Date: 12-10-2015
Abstract: Virtual screening of a drug database identified Carvedilol, Loratadine, Nefazodone and Astemizole as PAR2 antagonists, after ligand docking and molecular dynamics simulations using a PAR2 homology model and a putative binding mode of a known PAR2 ligand. The drugs demonstrated competitive binding and antagonism of calcium mobilization and ERK1/2 phosphorylation in CHO-hPAR2 transfected cells, while inhibiting IL-6 secretion in PAR2 expressing MDA-MB-231 breast cancer cells. This research highlights opportunities for GPCR hit-finding from FDA-approved drugs.
Tumor selectivity and transcriptional activation by azelaic bishydroxamic acid in human melanocytic cells.
Publisher: Elsevier BV
Date: 06-1997
DOI: 10.1016/S0006-2952(97)00016-6
Abstract: Azelaic bishydroxamic acid (ABHA), a potent differentiating agent for lymphoid cells, was selectively toxic for 5 human tumor cell lines and transformed human melanocytes and keratinocytes (dose for 37% survival, D37, 30-100 microg/mL) compared with normal cells (melanocytes, fibroblasts D37 > 300 microg/mL). Dendritic morphology was the only indicator found for increased differentiation, markers for the pigmentation pathway being unchanged or inhibited by ABHA. In contrast to hexamethylene bisacetamide and azelaic acid, ABHA significantly increased the HIV LTR, SV40 and c-fos promoter activities during a 24 hr treatment. Metallothionein promoter activity was enhanced by 5 hr treatment with ABHA in a sensitive melanoma cell line (MM96L) but was inhibited in a more resistant line (HeLa) c-fos promoter activity was inhibited in HeLa during this time. Transcription from a p53 binding response element was inhibited in MM96L by a 24 hr ABHA treatment but enhanced in HeLa. ABHA may represent a structural prototype for designing more potent and selective anti-melanoma agents.
MAIT cells regulate NK cell-mediated tumor immunity
Publisher: Springer Science and Business Media LLC
Date: 06-08-2021
DOI: 10.1038/S41467-021-25009-4
Abstract: The function of MR1-restricted mucosal-associated invariant T (MAIT) cells in tumor immunity is unclear. Here we show that MAIT cell-deficient mice have enhanced NK cell-dependent control of metastatic B16F10 tumor growth relative to control mice. Analyses of this interplay in human tumor s les reveal that high expression of a MAIT cell gene signature negatively impacts the prognostic significance of NK cells. Paradoxically, pre-pulsing tumors with MAIT cell antigens, or activating MAIT cells in vivo, enhances anti-tumor immunity in B16F10 and E0771 mouse tumor models, including in the context of established metastasis. These effects are associated with enhanced NK cell responses and increased expression of both IFN-γ-dependent and inflammatory genes in NK cells. Importantly, activated human MAIT cells also promote the function of NK cells isolated from patient tumor s les. Our results thus describe an activation-dependent, MAIT cell-mediated regulation of NK cells, and suggest a potential therapeutic avenue for cancer treatment.
Diversity of T Cells Restricted by the MHC Class I-Related Molecule MR1 Facilitates Differential Antigen Recognition
Publisher: Elsevier BV
Date: 2016
DOI: 10.1016/J.IMMUNI.2015.12.005
Abstract: A characteristic of mucosal-associated invariant T (MAIT) cells is the expression of TRAV1-2(+) T cell receptors (TCRs) that are activated by riboflavin metabolite-based antigens (Ag) presented by the MHC-I related molecule, MR1. Whether the MR1-restricted T cell repertoire and associated Ag responsiveness extends beyond these cells remains unclear. Here, we describe MR1 autoreactivity and folate-derivative reactivity in a discrete subset of TRAV1-2(+) MAIT cells. This recognition was attributable to CDR3β loop-mediated effects within a consensus TRAV1-2(+) TCR-MR1-Ag footprint. Furthermore, we have demonstrated differential folate- and riboflavin-derivative reactivity by a erse population of "atypical" TRAV1-2(-) MR1-restricted T cells. We have shown that TRAV1-2(-) T cells are phenotypically heterogeneous and largely distinct from TRAV1-2(+) MAIT cells. A TRAV1-2(-) TCR docks more centrally on MR1, thereby adopting a markedly different molecular footprint to the TRAV1-2(+) TCR. Accordingly, ersity within the MR1-restricted T cell repertoire leads to differing MR1-restricted Ag specificity.
Stereoelectronic Effects on Dienophile Separation Influence the Diels–Alder Synthesis of Molecular Clefts
Publisher: Figshare
Date: 2019
The molecular basis underpinning the potency and specificity of MAIT cell antigens
Publisher: Springer Science and Business Media LLC
Date: 02-03-2020
Histone deacetylases (HDAC) in physiological and pathological bone remodelling
Publisher: Elsevier BV
Date: 02-2017
DOI: 10.1016/J.BONE.2016.11.028
Abstract: Histone deacetylases (HDACs)
Identification and phenotype of MAIT cells in cattle and their response to bacterial infections
Publisher: Cold Spring Harbor Laboratory
Date: 10-11-2020
DOI: 10.1101/2020.11.09.374678
Abstract: Mucosal-associated invariant T (MAIT) cells are a population of innate-like T cells that utilise a semi-invariant T cell receptor (TCR) α chain and are restricted by the highly conserved antigen presenting molecule MR1. MR1 presents microbial riboflavin biosynthesis derived metabolites produced by bacteria and fungi. Consistent with their ability to sense ligands derived from bacterial sources, MAIT cells have been associated with the immune response to a variety of bacterial infections, such as Mycobacterium spp ., Salmonella spp. and Escherichia coli . To date, MAIT cells have been studied in humans, non-human primates and mice. However, they have only been putatively identified in cattle by PCR based methods no phenotypic or functional analyses have been performed. Here, we identified a MAIT cell population in cattle utilising MR1 tetramers and high-throughput TCR sequencing. Phenotypic analysis of cattle MAIT cells revealed features highly analogous to those of MAIT cells in humans and mice, including expression of an orthologous TRAV1-TRAJ33 TCR α chain, an effector memory phenotype irrespective of tissue localisation, and expression of the transcription factors PLZF and EOMES. We determined the frequency of MAIT cells in peripheral blood and multiple tissues, finding that cattle MAIT cells are enriched in mucosal tissues as well as in the mesenteric lymph node. Cattle MAIT cells were responsive to stimulation by 5-OP-RU and riboflavin biosynthesis competent bacteria in vitro . Furthermore, MAIT cells in milk increased in frequency in cows with mastitis. Following challenge with virulent Mycobacterium bovis , a causative agent of bovine tuberculosis and a zoonosis, peripheral blood MAIT cells expressed higher levels of perforin. Thus MAIT cells are implicated in the immune response to two major bacterial infections in cattle. These data suggest that MAIT cells are functionally highly conserved and that cattle are an excellent large animal model to study the role of MAIT cells in important zoonotic infections.
Comparative Sequence, Structure and Redox Analyses of Klebsiella pneumoniae DsbA Show That Anti-Virulence Target DsbA Enzymes Fall into Distinct Classes
Publisher: Public Library of Science (PLoS)
Date: 14-11-2013
Toward peptide-based inhibitors as therapies for Parkinson's disease
Publisher: Future Science Ltd
Date: 10-2015
DOI: 10.4155/FMC.15.139
Protease-activated receptor 2 does not contribute to renal inflammation or fibrosis in the obstructed kidney
Publisher: Wiley
Date: 31-07-2019
DOI: 10.1111/NEP.13635
Abstract: Protease-activated receptor 2 (PAR2) has been implicated in the development of renal inflammation and fibrosis. In particular, activation of PAR2 in cultured tubular epithelial cells induces extracellular signal-regulated kinase signalling and secretion of fibronectin, C-C Motif Chemokine Ligand 2 (CCL2) and transforming growth factor-β1 (TGF-β1), suggesting a role in tubulointerstitial inflammation and fibrosis. We tested this hypothesis in unilateral ureteric obstruction (UUO) in which ongoing tubular epithelial cell damage drives tubulointerstitial inflammation and fibrosis. Unilateral ureteric obstruction surgery was performed in groups (n = 9/10) of Par2-/- and wild type (WT) littermate mice which were killed 7 days later. Non-experimental mice were controls. Wild type mice exhibited a 5-fold increase in Par2 messenger RNA (mRNA) levels in the UUO kidney. In situ hybridization localized Par2 mRNA expression to tubular epithelial cells in normal kidney, with a marked increase in Par2 mRNA expression by tubular cells, including damaged tubular cells, in WT UUO kidney. Tubular damage (tubular dilation, increased KIM-1 and decreased α-Klotho expression) and tubular signalling (extracellular signal-regulated kinase phosphorylation) seen in WT UUO were not altered in Par2-/- UUO. In addition, macrophage infiltration, up-regulation of M1 (NOS2) and M2 (CD206) macrophage markers, and up-regulation of pro-inflammatory molecules (tumour necrosis factor, CCL2, interleukin-36α) in WT UUO kidney were unchanged in Par2-/- UUO. Finally, the accumulation of α-SMA+ myofibroblasts, deposition of collagen IV and expression of pro-fibrotic factors (CTGF, TGF-β1) were not different between WT and Par2-/- UUO mice. Protease-activated receptor 2 expression is substantially up-regulated in tubular epithelial cells in the obstructed kidney, but this does not contribute to the development of tubular damage, renal inflammation or fibrosis.
Activity of Recombinant Dengue 2 Virus NS3 Protease in the Presence of a Truncated NS2B Co-factor, Small Peptide Substrates, and Inhibitors
Publisher: Elsevier BV
Date: 12-2001
Consecutive cyclic pentapeptide modules form short α-helices that are very stable to water and denaturants
Publisher: Wiley
Date: 05-05-2004
Conformational Selection of Inhibitors and Substrates by Proteolytic Enzymes: Implications for Drug Design and Polypeptide Processing
Publisher: American Chemical Society (ACS)
Date: 11-03-2000
DOI: 10.1021/JM990315T
Abstract: Inhibitors of proteolytic enzymes (proteases) are emerging as prospective treatments for diseases such as AIDS and viral infections, cancers, inflammatory disorders, and Alzheimer's disease. Generic approaches to the design of protease inhibitors are limited by the unpredictability of interactions between, and structural changes to, inhibitor and protease during binding. A computer analysis of superimposed crystal structures for 266 small molecule inhibitors bound to 48 proteases (16 aspartic, 17 serine, 8 cysteine, and 7 metallo) provides the first conclusive proof that inhibitors, including substrate analogues, commonly bind in an extended beta-strand conformation at the active sites of all these proteases. Representative superimposed structures are shown for (a) multiple inhibitors bound to a protease of each class, (b) single inhibitors each bound to multiple proteases, and (c) conformationally constrained inhibitors bound to proteases. Thus inhibitor/substrate conformation, rather than sequence/composition alone, influences protease recognition, and this has profound implications for inhibitor design. This conclusion is supported by NMR, CD, and binding studies for HIV-1 protease inhibitors/substrates which, when preorganized in an extended conformation, have significantly higher protease affinity. Recognition is dependent upon conformational equilibria since helical and turn peptide conformations are not processed by proteases. Conformational selection explains the resistance of folded/structured regions of proteins to proteolytic degradation, the susceptibility of denatured proteins to processing, and the higher affinity of conformationally constrained 'extended' inhibitors/substrates for proteases. Other approaches to extended inhibitor conformations should similarly lead to high-affinity binding to a protease.
Comparative Agonist/Antagonist Responses in Mutant Human C5a Receptors Define the Ligand Binding Site
Publisher: Elsevier BV
Date: 05-2005
Crystal Structures of Highly Constrained Substrate and Hydrolysis Products Bound to HIV-1 Protease. Implications for the Catalytic Mechanism
Publisher: American Chemical Society (ACS)
Date: 03-2008
DOI: 10.1021/BI7023157
Abstract: HIV-1 protease is a key target in treating HIV infection and AIDS, with 10 inhibitors used clinically. Here we used an unusual hexapeptide substrate, containing two macrocyclic tripeptides constrained to mimic a beta strand conformation, linked by a scissile peptide bond, to probe the structural mechanism of proteolysis. The substrate has been cocrystallized with catalytically active synthetic HIV-1 protease and an inactive isosteric (D25N) mutant, and three-dimensional structures were determined (1.60 A). The structure of the inactive HIVPR(D25N)/substrate complex shows an intact substrate molecule in a single orientation that perfectly mimics the binding of conventional peptide ligands of HIVPR. The structure of the active HIVPR roduct complex shows two monocyclic hydrolysis products trapped in the active site, revealing two molecules of the N-terminal monocyclic product bound adjacent to one another, one molecule occupying the nonprime site, as expected, and the other monocycle binding in the prime site in the reverse orientation. The results suggest that both hydrolysis products are released from the active site upon cleavage and then rebind to the enzyme. These structures reveal that N-terminal binding of ligands is preferred, that the C-terminal site is more flexible, and that HIVPR can recognize substrate shape rather than just sequence alone. The product complex reveals three carboxylic acids in an almost planar orientation, indicating an unusual hexagonal homodromic complex between three carboxylic acids. The data presented herein regarding orientation of catalytic aspartates support the cleavage mechanism proposed by Northrop. The results imply strategies for design of inhibitors targeting the N-terminal side of the cleavage site or taking advantage of the flexibility in the protease domain that accommodates substrate/inhibitor segments C-terminal to the cleavage site.
Modulation of ligand selectivity by mutation of the first extracellular loop of the human C5a receptor 1 1Abbreviations: C5aR, human complement fragment 5a receptor; WT, wild-type; G105D, C5aR mutated
Publisher: Elsevier BV
Date: 06-2001
DOI: 10.1016/S0006-2952(01)00608-6
Abstract: The cyclic C5a receptor antagonist, phenylalanine [L-ornithine-proline-D-cyclohexylalanine-tryptophan-arginine] (F-[OPchaWR]), has approximately 1000-fold less affinity for the C5a receptor (C5aR) on murine polymorphonuclear leukocytes than on human. Analysis of C5aR from different species shows that a possible cause of this difference is the variation in the sequence of the first extracellular loop of the receptor. The mouse receptor contains Y at a position analogous to P(103) in the human receptor, and D at G(105). To test this hypothesis, we expressed human C5aR mutants (P(103)Y, G(105)D and the double mutant, P(103)Y/G(105)D) in RBL-2H3 cells and investigated the effects of these mutations on binding affinity and receptor activation. All three mutant receptors had a higher affinity for human C5a than the wild-type receptor, but showed no significant difference in the ability of F-[OPchaWR] to inhibit human C5a binding. However, all of the mutant receptors had substantially lower affinities for the weak agonist, C5a des Arg(74) (C5adR(74)), and two altered receptors (G(105)D and P(103)Y/G(105)D) had much lower affinities for the C-terminal C5a agonist peptide analogue, L-tyrosine-serine-phenylalanine-lysine-proline-methionine-proline-leucine-D-alanine-arginine (YSFKPMPLaR). Although it is unlikely that differences at these residues are responsible for variations in the potency of F-[OPchaWR] across species, residues in the first extracellular loop are clearly involved in the recognition of both C5a and C5a agonists. The complex effects of mutating these residues on the affinity and response to C5a, C5adR(74), and the peptide analogues provide evidence of different binding modes for these ligands on the C5aR.
De novo macrocyclic peptides for inhibiting, stabilizing, and probing the function of the retromer endosomal trafficking complex.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 03-12-2021
Abstract: Novel macrocyclic peptides are found that bind and modulate the function of the retromer membrane trafficking complex.
Protease inhibitors: Current status and future prospects
Publisher: American Chemical Society (ACS)
Date: 02-2000
DOI: 10.1021/JM990412M
Countering Cooperative Effects in Protease Inhibitors Using Constrained β-Strand-Mimicking Templates in Focused Combinatorial Libraries
Publisher: American Chemical Society (ACS)
Date: 19-02-2004
DOI: 10.1021/JM030337M
Abstract: A major problem in de novo design of enzyme inhibitors is the unpredictability of the induced fit, with the shape of both ligand and enzyme changing cooperatively and unpredictably in response to subtle structural changes within a ligand. We have investigated the possibility of d ening the induced fit by using a constrained template as a replacement for adjoining segments of a ligand. The template preorganizes the ligand structure, thereby organizing the local enzyme environment. To test this approach, we used templates consisting of constrained cyclic tripeptides, formed through side chain to main chain linkages, as structural mimics of the protease-bound extended beta-strand conformation of three adjoining amino acid residues at the N- or C-terminal sides of the scissile bond of substrates. The macrocyclic templates were derivatized to a range of 30 structurally erse molecules via focused combinatorial variation of nonpeptidic appendages incorporating a hydroxyethylamine transition-state isostere. Most compounds in the library were potent inhibitors of the test protease (HIV-1 protease). Comparison of crystal structures for five protease-inhibitor complexes containing an N-terminal macrocycle and three protease-inhibitor complexes containing a C-terminal macrocycle establishes that the macrocycles fix their surrounding enzyme environment, thereby permitting independent variation of acyclic inhibitor components with only local disturbances to the protease. In this way, the location in the protease of various acyclic fragments on either side of the macrocyclic template can be accurately predicted. This type of templating strategy minimizes the problem of induced fit, reducing unpredictable cooperative effects in one inhibitor region caused by changes to adjacent enzyme-inhibitor interactions. This idea might be exploited in template-based approaches to inhibitors of other proteases, where a beta-strand mimetic is also required for recognition, and also other protein-binding ligands where different templates may be more appropriate.
Complement component C2, inhibiting a latent serine protease in the classical pathway of complement activation
Publisher: American Chemical Society (ACS)
Date: 13-08-2009
DOI: 10.1021/BI900679R
Abstract: The innate immune response to infection or injury involves an antigen-antibody triggered classical pathway (CP) of complement activation, in which soluble and cell surface plasma proteins cooperatively effect elimination of foreign organisms and damaged host cells. However, protracted or dysfunctional complement activation can lead to inflammatory diseases. Complement component 2 bound to C4b is cleaved by classical (C1s) or lectin (MASP2) proteases to produce C4bC2a, a very short-lived C3 convertase (t(1/2) 2 min) that in turn cleaves C3 to C3a and C3b, leading ultimately to formation of Membrane Attack Complex (MAC) and lysis of bacteria and damaged cells. C2 has the same serine protease domain as C4bC2a but in an inactive zymogen-like conformation, requiring cofactor-induced conformational change for activity. Here, we show that C2 has catalytic protease activity in its own right above pH 7, in the absence of cofactor, processing C3 and C3-derived chromogenic peptide fragments. In contrast to the instability of C3 convertase (t(1/2) 2 min, pH 7), the C2 enzyme is indefinitely stable under alkaline conditions, facilitating studies of its catalytic properties and development of small molecule inhibitors. We characterize the catalytic activity of C2 against C3 and short paranitroanilide peptide substrates, and identify potent small molecule inhibitors of C2 that also inhibit classical pathway C3 convertase, MAC formation, and hemolysis of sensitized sheep erythrocytes. These results provide a new avenue and valuable new insights to inhibiting CP complement activation relevant to inflammatory diseases.
The first solution stucture of a single α-helical turn. A pentapeptide α-helix stabilized by a metal clip [20]
Publisher: American Chemical Society (ACS)
Date: 10-2000
DOI: 10.1021/JA002416I
Conformational Control by Thiazole and Oxazoline Rings in Cyclic Octapeptides of Marine Origin. Novel Macrocyclic Chair and Boat Conformations
Publisher: American Chemical Society (ACS)
Date: 1996
DOI: 10.1021/JA962260F
Inhibitors of cyclo-oxygenase-2 and secretory phospholipase A2 preserve bone architecture following ovariectomy in adult rats
Publisher: Elsevier BV
Date: 07-2006
DOI: 10.1016/J.BONE.2005.12.017
Abstract: Epidemiological evidence and in vitro data suggest that COX-2 is a key regulator of accelerated remodeling. Accelerated states of osteoblast and osteoclast activity are regulated by prostaglandins in vitro, but experimental evidence for specific roles of cyclooxygenase-2 (COX-2) and secretory phospholipase A2 (sPLA2) in activated states of remodeling in vivo is lacking. The aim of this study was to determine the effect of specific inhibitors of sPLA2-IIa and COX-2 on bone remodeling activated by estrogen deficiency in adult female rats. One hundred and twenty-four adult female Wistar rats were ovariectomized (OVX) or sham-operated. Rats commenced treatment 14 days after surgery with either vehicle, a COX-2 inhibitor (DFU at 0.02 mg/kg/day and 2.0 mg/kg/day) or a sPLA2-group-IIa inhibitor (KH064 at 0.4 mg/kg/day and 4.0 mg/kg/day). Treatment continued daily until rats were sacrificed at 70 days or 98 days post-OVX. The right tibiae were harvested, fixed and embedded in methylmethacrylate for structural histomorphometric bone analysis at the proximal tibial metaphysis. The specific COX-2 or sPLA2 inhibitors prevented ovariectomy-induced (OVX-induced) decreases in trabecular connectivity (P<0.05) suppressed the acceleration of bone resorption and maintained bone turnover at SHAM levels following OVX in the rat. The sPLA2 inhibitor significantly suppressed increases in osteoclast surface induced by OVX (P<0.05), while the effect of COX-2 inhibition was less marked. These findings demonstrate that inhibitors of COX-2 and sPLA2-IIa can effectively suppress OVX-induced bone loss in the adult rat by conserving trabecular bone mass and architecture through reduced bone remodeling and decreased resorptive activity. Moreover, we report an important role of sPLA2-IIa in osteoclastogenesis that may be independent of the COX-2 metabolic pathway in the OVX rat in vivo.
Product release is rate-limiting for catalytic processing by the Dengue virus protease
Publisher: Springer Science and Business Media LLC
Date: 29-11-2016
DOI: 10.1038/SREP37539
Abstract: Dengue Virus (DENV) is the most prevalent global arbovirus, yet despite an increasing burden to health care there are currently no therapeutics available to treat infection. A potential target for antiviral drugs is the two-component viral protease NS2B-NS3pro, which is essential for viral replication. Interactions between the two components have been investigated here by probing the effect on the rate of enzyme catalysis of key mutations in a mobile loop within NS2B that is located at the interface of the two components. Steady-state kinetic assays indicated that the mutations greatly affect catalytic turnover. However, single turnover and fluorescence experiments have revealed that the mutations predominantly affect product release rather than substrate binding. Fluorescence analysis also indicated that the addition of substrate triggers a near-irreversible change in the enzyme conformation that activates the catalytic centre. Based on this mechanistic insight, we propose that residues within the mobile loop of NS2B control product release and present a new target for design of potent Dengue NS2B-NS3 protease inhibitors.
Inhibition of HIV-1 proteinase by non-peptide carboxylates
Publisher: Elsevier BV
Date: 04-1991
DOI: 10.1016/0006-291X(91)90915-T
Abstract: Some simple dicarboxylates are among the first reported non-peptide inhibitors of HIV-1 proteinase. Only weak inhibition (IC50 greater than or equal to 10 microM) was observed but this may be significant since only two potential enzyme-binding groups are present. Dixon plots and preliminary kinetic data are reported and a possible mechanism for the inhibition is discussed. The dicarboxylates are long enough to engage the carboxylate side chains of Arg 8 and Arg 108 at either end of the 24A long substrate-binding groove. This mode of binding has not been proven but other molecules with similarly separated charged ends are equally effective inhibitors, perhaps indicating a common mechanism of inhibition. There is evidence that placing other functional groups on the inhibitor enables alternative interactions with the enzyme which can reduce inhibitor potency. We propose that incorporation of ionic binding groups in more elaborate and selective non-peptides may potentiate inhibition of HIV-1 proteinase.
Formation of mononuclear and chloro-bridged binuclear copper(II) complexes of patellamide D, a naturally occurring cyclic peptide: influence of anion and solvent
Publisher: Elsevier BV
Date: 11-2004
DOI: 10.1016/J.JINORGBIO.2004.08.005
Abstract: Patellamide D (patH(4)) is a cyclic octapeptide isolated from the ascidian Lissoclinum patella. The peptide possesses a 24-azacrown-8 macrocyclic structure containing two oxazoline and two thiazole rings, each separated by an amino acid. The present spectrophotometric, electron paramagnetic resonance (EPR) and mass spectral studies show that patellamide D reacts with CuCl(2) and triethylamine in acetonitrile to form mononuclear and binuclear copper(II) complexes containing chloride. Molecular modelling and EPR studies suggest that the chloride anion bridges the copper(II) ions in the binuclear complex [Cu(2)(patH(2))(mu-Cl)](+). These results contrast with a previous study employing both base and methanol, the latter substituting for chloride in the copper(II) complexes en route to the stable mu-carbonato binuclear copper(II) complex [Cu(2) (patH(2))(mu-CO(3))]. Solvent clearly plays an important role in both stabilising these metal ion complexes and influencing their chemical reactivities.
The use of live-animal micro-computed tomography to determine the effect of a novel phospholipase A2 inhibitor on alveolar bone loss in an in vivo mouse model of periodontitis.
Publisher: Wiley
Date: 27-04-2009
DOI: 10.1111/J.1600-0765.2008.01132.X
Abstract: Live-animal micro-computed tomography is a new and promising technique that can be used to quantify changes in bone volume for periodontal disease models. The major aim of this study was to develop the methodology of live-animal micro-computed tomography and to determine the effect of a novel secretory phospholipase A2 inhibitor on alveolar bone loss. Periodontitis was induced in mice by oral infection with Porphyromonas gingivalis over a period of 13 wk, and live-animal micro-computed tomography scans were taken at different time-points to determine bone volume changes with disease progression. This enabled conclusions to be made as to when treatment was most likely to be effective. In addition, the model was used to investigate a novel drug, the secretory phospholipase A2 inhibitor, KHO64, and its potential ability to inhibit osteoclast bone resorption and treat periodontitis. The results from live-animal micro-computed tomography scans revealed greater, statistically significant, bone volume loss in diseased mice compared with normal mice (p < 0.05). This corresponded to a larger area from the cemento-enamel junction to the alveolar bone crest, as assessed by stereo imaging (p < 0.001). These techniques can therefore detect and quantify alveolar bone loss. Both methods revealed that KHO64 had no significant effect on the volume of bone resorption. Live-animal micro-computed tomography is a robust, reproducible technique that clearly demonstrates significant time-dependent changes in alveolar bone volume in a small-animal model of periodontitis.
Effects of a new C5a receptor antagonist on C5a‐ and endotoxin‐ induced neutropenia in the rat
Publisher: Wiley
Date: 02-1999
HDAC inhibitors: modulating leukocyte differentiation, survival, proliferation and inflammation
Publisher: Wiley
Date: 25-10-2011
DOI: 10.1038/ICB.2011.88
Abstract: Therapeutic effects of histone deacetylase (HDAC) inhibitors in cancer models were first linked to their ability to cause growth arrest and apoptosis of tumor cells. It is now clear that these agents also have pleiotropic effects on angiogenesis and the immune system, and some of these properties are likely to contribute to their anti-cancer activities. It is also emerging that inhibitors of specific HDACs affect the differentiation, survival and/or proliferation of distinct immune cell populations. This is true for innate immune cells such as macrophages, as well as cells of the acquired immune system, for ex le, T-regulatory cells. These effects may contribute to therapeutic profiles in some autoimmune and chronic inflammatory disease models. Here, we review our current understanding of how classical HDACs (HDACs 1-11) and their inhibitors impact on differentiation, survival and proliferation of distinct leukocyte populations, as well as the likely relevance of these effects to autoimmune and inflammatory disease processes. The ability of HDAC inhibitors to modulate leukocyte survival may have implications for the rationale of developing selective inhibitors as anti-inflammatory drugs.
HDACs and their inhibitors in immunology: teaching anticancer drugs new tricks
Publisher: Wiley
Date: 2012
DOI: 10.1038/ICB.2011.105
Chemical Modulators of Mucosal Associated Invariant T Cells
Publisher: American Chemical Society (ACS)
Date: 20-08-2021
Structure-activity relationships for substrate-based inhibitors of human complement factor B
Publisher: American Chemical Society (ACS)
Date: 10-09-2009
DOI: 10.1021/JM900781M
Abstract: Human complement is a cascading network of plasma proteins important in immune defense, cooperatively effecting recognition, opsonization, destruction, and removal of pathogens and infected/damaged cells. Overstimulated or unregulated complement activation can result in immunoinflammatory diseases. Key serine proteases in this cascade are difficult to study due to their multiprotein composition, short lifetimes, formation on membranes, or serum circulation as inactive zymogens. Factor B is inactive at pH 7, but a catalytically active serine protease under alkaline conditions, enabling structure-activity relationship studies for 63 substrate-based peptide inhibitors with 4-7 residues and a C-terminal aldehyde. A potent factor B inhibitor was hexpeptide Ac-RLTbaLAR-H (IC(50) 250 nM, pH 9.5), which at pH 7 also blocked formation of membrane attack complex via the "alternative pathway" of complement activation and inhibited human complement mediated lysis of rabbit erythrocytes. Inhibitors of factor B may be valuable probes and drug leads for complement mediated immunity and disease.
Absence of mucosal-associated invariant T cells in a person with a homozygous point mutation in MR1
Publisher: American Association for the Advancement of Science (AAAS)
Date: 03-07-2020
DOI: 10.1126/SCIIMMUNOL.ABC9492
Abstract: A rare human allele renders MR1 unable to present microbially derived antigen, resulting in a selective loss of MAIT cells.
Constraining Cyclic Peptides To Mimic Protein Structure Motifs
Publisher: Wiley
Date: 06-10-2014
Abstract: Many proteins exert their biological activities through small exposed surface regions called epitopes that are folded peptides of well-defined three-dimensional structures. Short synthetic peptide sequences corresponding to these bioactive protein surfaces do not form thermodynamically stable protein-like structures in water. However, short peptides can be induced to fold into protein-like bioactive conformations (strands, helices, turns) by cyclization, in conjunction with the use of other molecular constraints, that helps to fine-tune three-dimensional structure. Such constrained cyclic peptides can have protein-like biological activities and potencies, enabling their uses as biological probes and leads to therapeutics, diagnostics and vaccines. This Review highlights ex les of cyclic peptides that mimic three-dimensional structures of strand, turn or helical segments of peptides and proteins, and identifies some additional restraints incorporated into natural product cyclic peptides and synthetic macrocyclic peptidomimetics that refine peptide structure and confer biological properties.
Linkage isomerism in the binding of pentapeptide Ac-His(Ala) 3 His-NH2 to (ethylenediamine)palladium(II): Effect of the binding mode on peptide conformation
Publisher: American Chemical Society (ACS)
Date: 13-09-2008
DOI: 10.1021/IC800970P
Abstract: The reaction of the pentapeptide Ac-His1-Ala2-Ala3-Ala4-His5-NH2 (AcHAAAHNH2) (1) with [Pd(en)(ONO2)2] (en = NH2CH2CH2NH2) in either DMF-d(7) or H2O:D2O (90%:10%) gave three linkage isomers of [Pd(en)(AcHAAAHNH2)](2+) (2), 2a, 2b, and 2c, which differ only in which pair of imidazole nitrogen atoms bind to Pd. In the most abundant isomer, 2a, Pd is bound by N1 from each of the two imidazole rings. In the minor isomers 2b and 2c, Pd is bound by N1(His1) and N3(His5) and by N3(His1) and N1(His5), respectively. The reactions of [Pd(en)(ONO2)2] with the N-methylated peptides Ac-(N3-MeHis)-Ala-Ala-Ala-(N3-MeHis)-NH2 (AcH*AAAH*NH2) (3), Ac-(N3-MeHis)-Ala-Ala-Ala-(N1-MeHis)-NH2 (AcH(*)AAAH(#)NH2) (4), and Ac-(N1-MeHis)-Ala-Ala-Ala-(N3-Me-His)-NH2 (AcH(#)AAAH(*)NH2) (5) each gave a single species [Pd(en)(peptide)](2+) in N,N-dimethylformamide (DMF) or aqueous solution, 7, 8, and 9, respectively, with Pd bound by the two nonmethylated imidazole nitrogen atoms in each case. These complexes were analogous to 2a, 2b, and 2c, respectively. Ac-(N1-MeHis)-Ala-Ala-Ala-(N1-MeHis)-NH2 (AcH(#)AAAH(#)NH2) (6) with [Pd(en)(ONO2)2] in DMF slowly gave a single product, [Pd(en)(AcH(#)AAAH(#)NH2)](2+) (10), in which Pd was bound by the N3 of each imidazole ring. The corresponding linkage isomer of 2 was not observed. Complex 10 was also the major product in aqueous solution, but other species were also present. All compounds were exhaustively characterized in solution by multinuclear 1D ((1)H , (13)C, and, with (15)N-labeled ethylenediamine, (15)N) and 2D (correlation spectroscopy, total correlation spectroscopy, transverse rotating-frame Overhauser effect spectroscopy (T-ROESY), heteronuclear multiple-bond correlation, and heteronuclear single quantum coherence) NMR spectra, circular dichroism (CD) spectra, electrospray mass spectroscopy, and reversed-phase high-performance liquid chromatography. ROESY spectra were used to calculate the structure of 2a, which contained a single turn of a peptide alpha helix in both DMF and water, the helix being better defined in DMF. The Pd(en)(2+) moiety was not used in structure calculations, but its location and coordination by one imidazole N1 from each histidine to form a 22-membered metallocycle were unambiguously established. Convergence of the structures was greatest when calculated with two hydrogen-bond constraints (Ala4 peptide NH...OC acetyl and His5 peptide NH...OC-His1) that were indicated by the low temperature dependence of these NH chemical shifts. Vicinal HN-CHalpha coupling constants and chemical shifts of alpha-H atoms were also consistent with a helical conformation. Similar long-range ROE correlations were observed for [Pd(en)(AcH(*)AAAH(*)NH2)](2+) (7), which displayed a CD spectrum in aqueous solution that suggested the presence of some helicity. Long-range ROE correlations were not observed for 8, 9, or 10, but a combination of NMR data and CD spectroscopy was interpreted in terms of the conformational behavior of the coordinated pentapeptide. Only for the linkage isomer [Pd(en)(AcH(*)AAAH(#)NH2)](2+) (8) was there evidence of a contribution from a helical conformation. The data for 8 were interpreted as interconversion between the helix and random coil conformations. Zn(2+) with peptides gave broad NMR peaks attributed to lability of this metal ion, while reactions of cis-[Pt(NH3)2(ONO2)2] were slow, giving a complex mixture of products rather than the macrochelate ring observed with Pd(en)(2+). In summary, these studies indicate that Pd(en)(2+) coordinates to histidine with similar preference for each of the two imidazole nitrogens, enabling the formation of up to four linkage isomers in its complexes with pentapeptides His-xxx-His. Only the N1-N1 linkage isomer that forms a 22-membered macrochelate ring is able to induce an alpha-helical peptide conformation, whereas the 20- and 21-membered rings of linkage isomers do not. This suggests that linkage isomeric mixtures may compromise histidine coordination to metal ions and reduce alpha-helicity.
An antagonist of human protease activated receptor‐2 attenuates PAR2 signaling, macrophage activation, mast cell degranulation, and collagen‐induced arthritis in rats
Publisher: Wiley
Date: 30-03-2012
DOI: 10.1096/FJ.11-201004
Abstract: Multiple serine proteases exert proinflammatory actions by signaling through protease-activated receptor-2 (PAR2) on the cell surface. Although inhibitors of in idual proteases are anti-inflammatory, we sought to discover whether the first potent antagonist of their common target PAR2 might be beneficial in treating chronic arthritis-like inflammatory disease. Using a fluorescence assay, a novel compound, GB88, was shown to antagonize PAR2-induced intracellular Ca(2+) release in human monocyte-derived macrophages, being 1000 times more potent than a control compound, ENMD-1068 (IC(50) 1.6 ± 0.5 μM vs. 1.2 ± 0.4 mM, respectively). In Wistar rats, GB88 was orally bioavailable (F=55%, T(max) 4 h, C(max) 1.7 μM, 10 mg/kg). GB88 inhibited the acute paw edema induced in Wistar rats by intraplantar λ-carrageenan or PAR2 agonists 2-furoyl-LIGRLO-NH(2) or mast cell β-tryptase, without inhibiting proteolytic activity of tryptase in vitro. In the chronic collagen-induced model of arthritis in rats, GB88 (10 mg/kg) was disease modifying and ameliorated pathological and histopathological changes (edema, pannus formation, synovial hyperplasia, collagen degradation, macrophage invasion, mast cell degranulation) compared to untreated arthritic controls. The results suggest that an orally active PAR2 antagonist is effective in treating chronic arthritis in rats through inhibiting macrophage infiltration, mast cell degranulation, and β-tryptase-PAR2 signaling in joint inflammation.
Small Molecule Inhibitors of Disulfide Bond Formation by the Bacterial DsbA–DsbB Dual Enzyme System
Publisher: American Chemical Society (ACS)
Date: 27-01-2015
DOI: 10.1021/CB500988R
Abstract: The DsbA:DsbB redox machinery catalyzes disulfide bond formation in secreted proteins and is required for bacterial virulence factor assembly. Both enzymes have been identified as targets for antivirulence drugs. Here, we report synthetic analogues of ubiquinone (dimedone derivatives) that inhibit disulfide bond formation (IC50∼1 μM) catalyzed by E. coli DsbA:DsbB. The mechanism involves covalent modification of a single free cysteine leaving other cysteines unmodified. A vinylogous anhydride in each inhibitor is cleaved by the thiol, which becomes covalently modified to a thioester by a propionyl substituent. Cysteines and lysines on DsbA and DsbB and a nonredox enzyme were modified in a manner that implies some specificity. Moreover, human thioredoxin was not inhibited under the same conditions that inhibited EcDsbA. This proof of concept work uses small molecules that target specific cysteines to validate the DsbA and DsbB dual enzyme system as a viable and potentially druggable antivirulence target.
Complement C3a and C5a receptors promote GVHD by suppressing mitophagy in recipient dendritic cells
Publisher: American Society for Clinical Investigation
Date: 20-12-2018
A convergent solution-phase synthesis of the macrocycle Ac-Phe-[Orn-Pro-D-Cha-Trp-Arg], a potent new antiinflammatory drug
Publisher: American Chemical Society (ACS)
Date: 05-2003
DOI: 10.1021/JO034228R
Abstract: Relatively few cyclic peptides have reached the pharmaceutical marketplace during the past decade, most produced through fermentation rather than made synthetically. Generally, this class of compounds is synthesized for research purposes on milligram scales by solid-phase methods, but if the potential of macrocyclic peptidomimetics is to be realized, low-cost larger scale solution-phase syntheses need to be devised and optimized to provide sufficient quantities for preclinical, clinical, and commercial uses. Here, we describe a cheap, medium-scale, solution-phase synthesis of the first reported highly potent, selective, and orally active antagonist of the human C5a receptor. This compound, Ac-Phe[Orn-Pro-d-Cha-Trp-Arg], known as 3D53, is a macrocyclic peptidomimetic of the human plasma protein C5a and displays excellent antiinflammatory activity in numerous animal models of human disease. In a convergent approach, two tripeptide fragments Ac-Phe-Orn(Boc)-Pro-OH and H-d-Cha-Trp(For)-Arg-OEt were first prepared by high-yielding solution-phase couplings using a mixed anhydride method before coupling them to give a linear hexapeptide which, after deprotection, was obtained in 38% overall yield from the commercially available amino acids. Cyclization in solution using BOP reagent gave the antagonist in 33% yield (13% overall) after HPLC purification. Significant features of the synthesis were that the Arg side chain was left unprotected throughout, the component Boc-d-Cha-OH was obtained very efficiently via hydrogenation of d-Phe with PtO(2) in TFA/water, the tripeptides were coupled at the Pro-Cha junction to minimize racemization via the oxazolone pathway, and the entire synthesis was carried out without purification of any intermediates. The target cyclic product was purified (>97%) by reversed-phase HPLC. This convergent synthesis with minimal use of protecting groups allowed batches of 50-100 g to be prepared efficiently in high yield using standard laboratory equipment. This type of procedure should be useful for making even larger quantities of this and other macrocyclic peptidomimetic drugs.
Contiguous hydrophobic and charged surface patches in short helix-constrained peptides drive cell permeability
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C7OB02952G
Abstract: Different ways to get peptides into cells.
Agonists and antagonists of protease activated receptors (PARs)
Publisher: Bentham Science Publishers Ltd.
Date: 02-2006
DOI: 10.2174/092986706775476070
Abstract: Protease activated receptors (PARs) are a category of G-protein coupled receptors (GPCRs) implicated in the progression of a wide range of diseases, including thrombosis, inflammatory disorders, and proliferative diseases. Signal transduction via PARs proceeds via an unusual activation mechanism. Instead of being activated through direct interaction with an extracellular signal like most GPCRs, they are self-activated following cleavage of their extracellular N-terminus by serine proteases to generate a new receptor N-terminus that acts as an intramolecular ligand by folding back onto itself and triggering receptor activation. Short synthetic peptides corresponding to this newly exposed N-terminal tethered ligand can activate three of the four known PARs in the absence of proteases, and such PAR activating peptides (PAR-APs) have served as templates for agonist/antagonist development. In fact much of the evidence for involvement of PARs in diseases has relied upon use of PAR-APs, often of low potency and uncertain selectivity. This review summarizes current structures of PAR agonists and antagonists, the need for more selective and more potent PAR ligands that activate or antagonize this intriguing class of receptors, and outlines the background relevant to PAR activation, assay methods, and physiological properties anticipated for PAR ligands.
Targeting histone deacetylase inhibitors for anti-malarial therapy
Publisher: Bentham Science Publishers Ltd.
Date: 02-2009
DOI: 10.2174/156802609788085313
Abstract: It is now clear that histone acetylation plays key roles in regulating gene transcription in both eukaryotes and prokaryotes, the acetylated form inducing gene expression while deacetylation silences genes. Recent studies have identified roles for histone acetyltransferases (HATs) and/or histone deacetylases (HDACs) in a number of parasites including Entamoeba histolytica, Toxoplasma gondii, Schistosoma mansoni, Cryptosporidium sp., Leishmania donovani, Neospora caninum, and Plasmodium falciparum. Here we survey fairly limited efforts to date in profiling antimalarial activities of HDAC inhibitors, showing that such compounds are potent inhibitors of the growth of P. falciparum in vitro and in vivo. Most of the compounds evaluated so far have borne a zinc-binding hydroxamate group that tends to be metabolized in vivo, and thus new zinc-binding groups need to be incorporated into second generation inhibitors in order to mask the catalytic zinc in the active site of HDACs. Also the development of compounds that are selective for parasitic HDACs over mammalian HDACs is still in relative infancy and it will take some time to derive antiparasitic HDAC inhibitor compounds with minimal toxicity for the host and acceptable pharmacokinetic and pharmacodynamic profiles for human treatment. Nevertheless, results to date suggest that HDAC inhibitor development represents a promising new approach to the potential treatment of parasitic infections, including those induced by malaria protozoa, and may offer new therapeutic targets within increasingly drug-resistant malarial parasites.
Intravenous immunoglobulin (IVIG) protects the brain against experimental stroke by preventing complement-mediated neuronal cell death
Publisher: Proceedings of the National Academy of Sciences
Date: 28-08-2007
Abstract: Stroke is among the three leading causes of death worldwide and the most frequent cause of permanent disability. Brain ischemia induces an inflammatory response involving activated complement fragments. Here we show that i.v. Ig (IVIG) treatment, which scavenges complement fragments, protects brain cells against the deleterious effects of experimental ischemia and reperfusion (I/R) and prevents I/R-induced mortality in mice. Animals administered IVIG either 30 min before ischemia or after 3 h of reperfusion exhibited a 50–60% reduction of brain infarct size and a 2- to 3-fold improvement of the functional outcome. Even a single low dose of IVIG given after stroke was effective. IVIG was protective in the nonreperfusion model of murine stroke as well and did not exert any peripheral effects. Human IgG as well as intrinsic murine C3 levels were significantly higher in the infarcted brain region compared with the noninjured side, and their physical association was demonstrated by immuno-coprecipitation. C5-deficient mice were significantly protected from I/R injury compared with their wild-type littermates. Exposure of cultured neurons to oxygen/glucose deprivation resulted in increased levels of C3 associated with activation of caspase 3, a marker of apoptosis both signals were attenuated with IVIG treatment. Our data suggest a major role for complement-mediated cell death in ischemic brain injury and the prospect of using IVIG in relatively low doses as an interventional therapy for stroke.
A molecular basis underpinning the T cell receptor heterogeneity of mucosal-associated invariant T cells
Publisher: Rockefeller University Press
Date: 21-07-2014
DOI: 10.1084/JEM.20140484
Abstract: Mucosal-associated invariant T (MAIT) cells express an invariant T cell receptor (TCR) α-chain (TRAV1-2 joined to TRAJ33, TRAJ20, or TRAJ12 in humans), which pairs with an array of TCR β-chains. MAIT TCRs can bind folate- and riboflavin-based metabolites restricted by the major histocompatibility complex (MHC)-related class I−like molecule, MR1. However, the impact of MAIT TCR and MR1-ligand heterogeneity on MAIT cell biology is unclear. We show how a previously uncharacterized MR1 ligand, acetyl-6-formylpterin (Ac-6-FP), markedly stabilized MR1, potently up-regulated MR1 cell surface expression, and inhibited MAIT cell activation. These enhanced properties of Ac-6-FP were attributable to structural alterations in MR1 that subsequently affected MAIT TCR recognition via conformational changes within the complementarity-determining region (CDR) 3β loop. Analysis of seven TRBV6-1+ MAIT TCRs demonstrated how CDR3β hypervariability impacted on MAIT TCR recognition by altering TCR flexibility and contacts with MR1 and the Ag itself. Ternary structures of TRBV6-1, TRBV6-4, and TRBV20+ MAIT TCRs in complex with MR1 bound to a potent riboflavin-based antigen (Ag) showed how variations in TRBV gene usage exclusively impacted on MR1 contacts within a consensus MAIT TCR-MR1 footprint. Moreover, differential TRAJ gene usage was readily accommodated within a conserved MAIT TCR-MR1-Ag docking mode. Collectively, MAIT TCR heterogeneity can fine-tune MR1 recognition in an Ag-dependent manner, thereby modulating MAIT cell recognition.
Quinazolinone derivatives as inhibitors of homologous recombinase RAD51
Publisher: Elsevier BV
Date: 07-2017
DOI: 10.1016/J.BMCL.2017.05.039
Abstract: RAD51 is a vital component of the homologous recombination DNA repair pathway and is overexpressed in drug-resistant cancers, including aggressive triple negative breast cancer (TNBC). A proposed strategy for improving therapeutic outcomes for patients is through small molecule inhibition of RAD51, thereby sensitizing tumor cells to DNA damaging irradiation and/or chemotherapy. Here we report structure-activity relationships for a library of quinazolinone derivatives. A novel RAD51 inhibitor (17) displays up to 15-fold enhanced inhibition of cell growth in a panel of TNBC cell lines compared to compound B02, and approximately 2-fold increased inhibition of irradiation-induced RAD51 foci formation. Additionally, compound 17 significantly inhibits TNBC cell sensitivity to DNA damage, implying a potentially targeted therapy for cancer treatment.
Regioselective structural and functional mimicry of peptides. Design of hydrolytically-stable cyclic peptidomimetic inhibitors of HIV-1 protease
Publisher: American Chemical Society (ACS)
Date: 10-1995
DOI: 10.1021/JA00146A007
Potencies of Human Immunodeficiency Virus Protease Inhibitors In Vitro against Plasmodium falciparum and In Vivo against Murine Malaria
Publisher: American Society for Microbiology
Date: 02-2006
DOI: 10.1128/AAC.50.2.639-648.2006
Abstract: Parasite resistance to antimalarial drugs is a serious threat to human health, and novel agents that act on enzymes essential for parasite metabolism, such as proteases, are attractive targets for drug development. Recent studies have shown that clinically utilized human immunodeficiency virus (HIV) protease inhibitors can inhibit the in vitro growth of Plasmodium falciparum at or below concentrations found in human plasma after oral drug administration. The most potent in vitro antimalarial effects have been obtained for parasites treated with saquinavir, ritonavir, or lopinavir, findings confirmed in this study for a genetically distinct P. falciparum line (3D7). To investigate the potential in vivo activity of antiretroviral protease inhibitors (ARPIs) against malaria, we examined the effect of ARPI combinations in a murine model of malaria. In mice infected with Plasmodium chabaudi AS and treated orally with ritonavir-saquinavir or ritonavir-lopinavir, a delay in patency and a significant attenuation of parasitemia were observed. Using modeling and ligand docking studies we examined putative ligand binding sites of ARPIs in aspartyl proteases of P. falciparum (plasmepsins II and IV) and P. chabaudi (plasmepsin) and found that these in silico analyses support the antimalarial activity hypothesized to be mediated through inhibition of these enzymes. In addition, in vitro enzyme assays demonstrated that P. falciparum plasmepsins II and IV are both inhibited by the ARPIs saquinavir, ritonavir, and lopinavir. The combined results suggest that ARPIs have useful antimalarial activity that may be especially relevant in geographical regions where HIV and P. falciparum infections are both endemic.
Drugs and drug-like molecules can modulate the function of mucosal-associated invariant T cells
Publisher: Springer Science and Business Media LLC
Date: 06-02-2017
DOI: 10.1038/NI.3679
Abstract: The major-histocompatibility-complex-(MHC)-class-I-related molecule MR1 can present activating and non-activating vitamin-B-based ligands to mucosal-associated invariant T cells (MAIT cells). Whether MR1 binds other ligands is unknown. Here we identified a range of small organic molecules, drugs, drug metabolites and drug-like molecules, including salicylates and diclofenac, as MR1-binding ligands. Some of these ligands inhibited MAIT cells ex vivo and in vivo, while others, including diclofenac metabolites, were agonists. Crystal structures of a T cell antigen receptor (TCR) from a MAIT cell in complex with MR1 bound to the non-stimulatory and stimulatory compounds showed distinct ligand orientations and contacts within MR1, which highlighted the versatility of the MR1 binding pocket. The findings demonstrated that MR1 was able to capture chemically erse structures, spanning mono- and bicyclic compounds, that either inhibited or activated MAIT cells. This indicated that drugs and drug-like molecules can modulate MAIT cell function in mammals.
Therapeutic targets in inflammatory disease
Publisher: Bentham Science Publishers Ltd.
Date: 12-2005
DOI: 10.2174/092986705774462923
Abstract: This commentary is an introduction to a special issue on "Latest Developments in the Treatment of Inflammation". It outlines some key events in the inflammatory response to infection or injury and describes some of the important drug targets of relevance to the succeeding articles, which survey inhibitors of these targets as prospective or current antiinflammatory drugs. It also highlights important limitations in the validation of inflammatory drug targets, and in the rate of discovery and development of new antiinflammatory drugs.
Histone deacetylases as regulators of inflammation and immunity
Publisher: Elsevier BV
Date: 07-2011
Abstract: Histone deacetylases (HDACs) remove an acetyl group from lysine residues of target proteins to regulate cellular processes. Small-molecule inhibitors of HDACs cause cellular growth arrest, differentiation and/or apoptosis, and some are used clinically as anticancer drugs. In animal models, HDAC inhibitors are therapeutic for several inflammatory diseases, but exacerbate atherosclerosis and compromise host defence. Loss of HDAC function has also been linked to chronic lung diseases in humans. These contrasting effects might reflect distinct roles for in idual HDACs in immune responses. Here, we review the current understanding of innate and adaptive immune pathways that are regulated by classical HDAC enzymes. The objective is to provide a rationale for targeting (or not targeting) in idual HDAC enzymes with inhibitors for future immune-related applications.
Membrane-anchored Serine Protease Matriptase Is a Trigger of Pulmonary Fibrogenesis
Publisher: American Thoracic Society
Date: 15-04-2016
PAR2-induced inflammatory responses in human kidney tubular epithelial cells
Publisher: American Physiological Society
Date: 15-03-2013
DOI: 10.1152/AJPRENAL.00540.2012
Abstract: Protease-activated receptor-2 (PAR2) is a G protein-coupled receptor abundantly expressed in the kidney. The aim of this study was to profile inflammatory gene and protein expression induced by PAR2 activation in human kidney tubular epithelial cells (HTEC). A novel PAR2 antagonist, GB88, was used to confirm agonist specificity. Intracellular Ca 2+ (iCa 2+ ) mobilization, confocal microscopy, gene expression profiling, qRTPCR, and protein expression were used to characterize PAR2 activation. PAR2 induced a pronounced increase in iCa 2+ concentration that was blocked by the PAR2 antagonist. Treatment with SLIGKV-NH 2 at the apical or basolateral cell surface for 5 h induced expression of a range of inflammatory genes by greater than fourfold, including IL-1β, TRAF1, IL-6, and MMP-1, as assessed by cDNA microarray and qRTPCR analysis. Using antibody arrays, GM-CSF, ICAM-1, TNF-α, MMP-1, and MMP-10 were among the induced proteins secreted. Cytokine-specific ELISAs identified three- to sixfold increases in GM-CSF, IL-6, IL-8, and TNF-α, which were blocked by GB88 and protein kinase C inhibitors. Treatment of cells at the basolateral surface induced more potent inflammatory responses, with release of MCP-1 and fibronectin to the apical and basolateral compartments apical treatment only increased secretion of these factors to the apical compartment. PAR2 activation at the basolateral surface dramatically reduced transepithelial electrical resistance (TEER) whereas apical treatment had no effect. There was very little leakage ( %) of peptides across the cell monolayer (liquid chromatography-mass spectrometry). In summary, SLIGKV-NH 2 induced robust proinflammatory responses in HTEC that were antagonized by GB88. These results suggest that PAR2 antagonists could be useful disease-modifying, anti-inflammatory agents in kidney disease.
Francisella tularensis induces Th1 like MAIT cells conferring protection against systemic and local infection
Publisher: Springer Science and Business Media LLC
Date: 16-07-2021
DOI: 10.1038/S41467-021-24570-2
Abstract: Mucosal-associated Invariant T (MAIT) cells are recognized for their antibacterial functions. The protective capacity of MAIT cells has been demonstrated in murine models of local infection, including in the lungs. Here we show that during systemic infection of mice with Francisella tularensis live vaccine strain results in evident MAIT cell expansion in the liver, lungs, kidney and spleen and peripheral blood. The responding MAIT cells manifest a polarised Th1-like MAIT-1 phenotype, including transcription factor and cytokine profile, and confer a critical role in controlling bacterial load. Post resolution of the primary infection, the expanded MAIT cells form stable memory-like MAIT-1 cell populations, suggesting a basis for vaccination. Indeed, a systemic vaccination with synthetic antigen 5-(2-oxopropylideneamino)-6- d -ribitylaminouracil in combination with CpG adjuvant similarly boosts MAIT cells, and results in enhanced protection against both systemic and local infections with different bacteria. Our study highlights the potential utility of targeting MAIT cells to combat a range of bacterial pathogens.
A dual-purpose synthetic colloidal platform for protease mapping: substrate profiling for Dengue and West Nile virus proteases
Publisher: Elsevier BV
Date: 05-2008
Abstract: In a proof of concept study, we created a small focused fluorescent hexapeptide library onto 14 multiplexed barcoded sets of silica particles to probe the substrate recognition specificity of West Nile and Dengue virus proteases. A flow cytometric analysis demonstrated that the optical signature of each bead population remained distinguishable throughout the solid-phase peptide synthesis and proteolytic assay. As expected, both proteases displayed a narrow specificity for lysine and arginine residues in the P(1) and P(2) substrate positions. This open-ended platform enables the fast and simultaneous identification of peptide substrates and is applicable to other proteases.
Diverse MR1-restricted T cells in mice and humans
Publisher: Springer Science and Business Media LLC
Date: 21-05-2019
DOI: 10.1038/S41467-019-10198-W
Abstract: Mucosal-associated invariant T (MAIT) cells express an invariant TRAV1/TRAJ33 TCR-α chain and are restricted to the MHC-I-like molecule, MR1. Whether MAIT cell development depends on this invariant TCR-α chain is unclear. Here we generate Traj33 -deficient mice and show that they are highly depleted of MAIT cells however, a residual population remains and can respond to exogenous antigen in vitro or pulmonary Legionella challenge in vivo. These residual cells include some that express Trav1 + TCRs with conservative Traj -gene substitutions, and others that express Trav1 - TCRs with a broad range of Traj genes. We further report that human TRAV1-2 - MR1-restricted T cells contain both MAIT-like and non-MAIT-like cells, as judged by their TCR repertoire, antigen reactivity and phenotypic features. These include a MAIT-like population that expresses a public, canonical TRAV36 + TRBV28 + TCR. Our findings highlight the TCR ersity and the resulting potential impact on antigen recognition by MR1-restricted T cells.
Hepatic expression profiling identifies steatosis-independent and steatosis-driven advanced fibrosis genes
Publisher: American Society for Clinical Investigation
Date: 25-07-2018
Targeting Class IIa HDACs: Insights from Phenotypes and Inhibitors
Publisher: Bentham Science Publishers Ltd.
Date: 12-2021
DOI: 10.2174/0929867328666210629160647
Abstract: This review summarizes key literature defining the phenotypes of in idual class IIa HDAC proteins and compounds that selectively target their enzymatic catalytic domain (CD). The focus is on the effects of class IIa HDACs in physiological and pathological conditions, both in vitro and in vivo, and on their mode of action in regulating genes, upstream proteins and signaling pathways. Phenotype studies further demonstrate either beneficial or detrimental effects of silencing selected class IIa HDACs or their enzymatic properties. We also summarize the knowledge gained from structure-activity relationships of CD inhibitors as well as molecular mechanisms underpinning isozyme selectivity where crystal structures or modelling studies are available. Given that the number of genes affected by silencing class IIa HDACs is much smaller than class I, the role of gene regulation of class IIa HDACs could be much more selective. Since class IIa HDACs have restricted tissue distributions and multiple functions independent of their CD, targeting the CD of class IIa HDACs could lead to more selective therapeutic agents with significantly fewer side-effects than other HDAC ligands.
C5a, but not C5a-des Arg, induces upregulation of heteromer formation between complement C5a receptors C5aR and C5L2
Publisher: Wiley
Date: 24-09-2013
DOI: 10.1038/ICB.2013.48
Abstract: Receptors for C5a have an important role in innate immunity and inflammation where their expression and activation is tightly regulated. There are two known receptors for C5a: the C5a receptor (C5aR) and the C5a receptor like-2 (C5L2) receptor. Here we hypothesized that activation of C5aR might lead to heteromer formation with C5L2, as a downregulatory mechanism for C5aR signaling. To investigate this experimentally, bioluminescent resonance energy transfer (BRET) was implemented and supported by wide-field microscopy to analyze receptor localization in transfected HEK293 cells and human monocyte-derived macrophages (HMDM). BRET experiments indicated the presence of constitutive C5aR-C5L2 heteromers, where C5a, but not C5a-des Arg, was able to induce further heteromer formation, which was inhibited by a C5aR-specific antagonist. The data obtained suggest that C5aR-C5L2 can form heteromers in a process enhanced by C5a, but not by C5a-des Arg. There was also a significant difference in the levels of the anti-inflammatory cytokine IL-10 detected in HMDM following exposure to C5a compared with that seen for C5a-des Arg but no differences in the pro-inflammatory cytokines TNFα and IL-6. These subtle differences in C5a and C5a-des Arg induced receptor function may be of benefit in understanding the regulation of C5a in acute inflammation.
Small molecules that mimic components of bioactive protein surfaces
Publisher: CSIRO Publishing
Date: 2004
DOI: 10.1071/CH04074
Abstract: Small molecules designed to mimic specific structural components of a protein (peptide strands, sheets, turns, helices, or amino acids) can be expected to display agonist or antagonist biological responses by virtue of interacting with the same receptors that recognize the protein. Here we describe some minimalist approaches to structural mimetics of amino acids and of strand, turn, or helix segments of proteins. The designed molecules show potent and selective inhibition of protease, transferase, and phospholipase enzymes, or antagonism of G-protein coupled or transcriptional receptors, and have potent anti-tumour, anti-inflammatory, or antiviral activity.
Zinc monoglycerolate - A slow-release source of therapeutic zinc: Solubilization by endogenous ligands
Publisher: Springer Science and Business Media LLC
Date: 05-1992
DOI: 10.1007/BF01991243
Abstract: According to clinical trials literature, every person with a schizophrenic disorder should be provided with the combination of optimal dose antipsychotics, strategies to educate himself and his carers to cope more efficiently with environmental stresses, cognitive-behavioural strategies to enhance work and social goals and reducing residual symptoms, and assertive home-based management to help prevent and resolve major social needs and crises, including recurrent episodes of symptoms. Despite strong scientific support for the routine implementation of these 'evidence-based' strategies, few services provide more than the pharmacotherapy component, and even this is seldom applied in the manner associated with the best results in the clinical trials. An international collaborative group, the Optimal Treatment Project (OTP), has been developed to promote the routine use of evidence-based strategies for schizophrenic disorders. A field trial was started to evaluate the benefits and costs of applying evidence-based strategies over a 5-year period. Centres have been set up in 18 countries. This paper summarises the outcome after 24 months of 'optimal' treatment in 603 cases who had reached this stage in their treatment by the end of 2002. On all measures the evidence-based OTP approach achieved more than double the benefits associated with current best practices. One half of recent cases had achieved full recovery from clinical and social morbidity. These advantages were even more striking in centres where a random-control design was used.
Nonpeptidic ligands for peptide-activated G protein-coupled receptors
Publisher: American Chemical Society (ACS)
Date: 07-2007
DOI: 10.1021/CR050984G
A Selective and Versatile Synthesis of Substituted Chromones via Addition of Phenols to Dimethyl Acetylenedicarboxylate
Publisher: CSIRO Publishing
Date: 1995
DOI: 10.1071/CH9950677
Abstract: Despite many published syntheses of chromones, none has been reported to be both selective for chromones and tolerant of ring substitution. The addition of substituted phenols to dimethyl acetylenedicarboxylate is now reported as a versatile high yield initial step in a simple three-step synthesis of chromone 2-carboxylic acids. Triethylamine being used to deprotonate the substituted phenol, the addition to dimethyl acetylenedicarboxylate proceeds under mild conditions and tolerates a wide range of functional groups on the phenol. Although not stereoselective, both fumarate and maleate aryloxy products of this addition can then be cyclized, according to a known method, to chromones without contamination by isomeric coumarins. Thus the addition reaction is a valuable component of a versatile and selective synthesis of substituted chromones.
An interaction between the methyltransferase and RNA dependent RNA polymerase domains of the West Nile virus NS5 protein
Publisher: Microbiology Society
Date: 09-2013
Abstract: The flavivirus nonstructural protein 5 (NS5) is a large protein that is structurally conserved among members of the genus, making it an attractive target for antiviral drug development. The protein contains a methyltransferase (MTase) domain and an RNA dependent RNA polymerase (POL) domain. Previous studies with dengue viruses have identified a genetic interaction between residues 46–49 in the αA3-motif in the MTase and residue 512 in POL. These genetic interactions are consistent with structural modelling of these domains in West Nile virus (WNV) NS5 that predict close proximity of these regions of the two domains, and potentially a functional interaction mediated via the αA3-motif. To demonstrate an interaction between the MTase and POL domains of the WNV NS5 protein, we co-expressed affinity-tagged recombinant MTase and POL proteins in human embryonic kidney cells with simian virus 40 large T antigen (HEK293T cells) and performed pulldown assays using an antibody to the flag tag on POL. Western blot analysis with an anti-MTase mAb revealed that the MTase protein was specifically co-immunoprecipitated with POL, providing the first evidence of a specific interaction between these domains. To further assess the role of the αA3 helix in this interaction, selected residues in this motif were mutated in the recombinant MTase and the effect on POL interaction determined by the pulldown assay. These mutations were also introduced into a WNV infectious clone (FLSDX) and the replication properties of these mutant viruses assessed. While none of the αA3 mutations had a significant effect on the MTase–POL association in pulldown assays, suggesting that these residues were not specific to the interaction, an E46L mutation completely abolished virus viability indicating a critical requirement of this residue in replication. Failure to generate compensatory mutations in POL to rescue replication, even after several passages of the transfection supernatant in Vero cells, precluded further conclusion of the role of this residue in the context of MTase–POL interactions.
Studies of the interaction of potassium(I), calcium(II), magnesium(II), and copper(II) with cyclosporin A
Publisher: Elsevier BV
Date: 10-2003
DOI: 10.1016/S0162-0134(03)00288-5
Abstract: Metal ion binding properties of the immunosuppressant drug cyclosporin A have been investigated. Complexation studies in acetonitrile solution using 1H NMR and CD spectroscopy yielded 1:1 metal-peptide binding constants (log(10)K) for potassium(I), <1, magnesium(II), 4.8+/-0.2, and calcium(II), 5.0+/-1.0. The interaction of copper(II) with cyclosporin A in methanol was investigated with UV/visible and electron paramagnetic resonance (EPR) spectroscopy. No complexation of copper(II) was observed in neutral solution. In the presence of base, monomeric copper(II) complexes were detected. These results support the possibility that cyclosporin A has ionophoric properties for biologically important essential metal ions.
Inhibition of HIV-1 proteinase by metal ions
Publisher: Elsevier BV
Date: 06-1992
DOI: 10.1016/0020-711X(92)90096-J
Abstract: 1. Certain metal ions have been identified as inhibitors (IC50 1-20 microM) of the aspartic proteinase of Human Immunodeficiency Virus Type 1 (HIV-PR). 2. By contrast most simple metal ions do not inhibit this enzyme. 3. Those that did inhibit have in common a high charge/size ratio or "hard" acidic nature, preferring to combine covalently with oxygen donor ligands. 4. Some evidence from independent X-ray crystal structure determinations suggests that the metalloinhibitors identified here may bind in the active site of the enzyme via coordination to the carboxylate side chains of the essential active site residues Asp 25 and 125. 5. Although the measured inhibition is only microM, very few enzyme-inhibitor interactions can be taking place and so more complex metalloinhibitors with ligands that can also bind to peptide side chains of the enzyme might be significantly more potent inhibitors of HIV-PR and of viral replication.
Molecular recognition of macrocyclic peptidomimetic inhibitors by HIV-1 protease.
Publisher: American Chemical Society (ACS)
Date: 06-1999
DOI: 10.1021/BI990174X
Mirror image pairs of cyclic hexapeptides have different oral bioavailabilities and metabolic stabilities
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9CC06234C
Abstract: Rule-of-five parameters and membrane permeabilities are not the only determinants of oral bioavailability.
Synthesis, stability, antiviral activity, and protease-bound structures of substrate-mimicking constrained macrocyclic inhibitors of HIV-1 protease
Publisher: American Chemical Society (ACS)
Date: 25-08-2000
DOI: 10.1021/JM000013N
Abstract: Three new peptidomimetics (1-3) have been developed with highly stable and conformationally constrained macrocyclic components that replace tripeptide segments of protease substrates. Each compound inhibits both HIV-1 protease and viral replication (HIV-1, HIV-2) at nanomolar concentrations without cytotoxicity to uninfected cells below 10 microM. Their activities against HIV-1 protease (K(i) 1.7 nM (1), 0.6 nM (2), 0.3 nM (3)) are 1-2 orders of magnitude greater than their antiviral potencies against HIV-1-infected primary peripheral blood mononuclear cells (IC(50) 45 nM (1), 56 nM (2), 95 nM (3)) or HIV-1-infected MT2 cells (IC(50) 90 nM (1), 60 nM (2)), suggesting suboptimal cellular uptake. However their antiviral potencies are similar to those of indinavir and renavir under identical conditions. There were significant differences in their capacities to inhibit the replication of HIV-1 and HIV-2 in infected MT2 cells, 1 being ineffective against HIV-2 while 2 was equally effective against both virus types. Evidence is presented that 1 and 2 inhibit cleavage of the HIV-1 structural protein precursor Pr55(gag) to p24 in virions derived from chronically infected cells, consistent with inhibition of the viral protease in cells. Crystal structures refined to 1.75 A (1) and 1.85 A (2) for two of the macrocyclic inhibitors bound to HIV-1 protease establish structural mimicry of the tripeptides that the cycles were designed to imitate. Structural comparisons between protease-bound macrocyclic inhibitors, VX478 ( renavir), and L-735,524 (indinavir) show that their common acyclic components share the same space in the active site of the enzyme and make identical interactions with enzyme residues. This substrate-mimicking minimalist approach to drug design could have benefits in the context of viral resistance, since mutations which induce inhibitor resistance may also be those which prevent substrate processing.
Truncated Glucagon-like Peptide-1 and Exendin-4 α-Conotoxin pl14a Peptide Chimeras Maintain Potency and α-Helicity and Reveal Interactions Vital for cAMP Signaling in Vitro
Publisher: Elsevier BV
Date: 07-2016
Metal Clips Induce Folding of a Short Unstructured Peptide into an α-Helix via Turn Conformations in Water. Kinetic versus Thermodynamic Products
Publisher: American Chemical Society (ACS)
Date: 29-10-2004
DOI: 10.1021/JA0453782
Abstract: Short peptides corresponding to two to four alpha-helical turns of proteins are not thermodynamically stable helices in water. Unstructured octapeptide Ac-His1-Ala2-Ala3-His4-His5-Glu6-Leu7-His8-NH(2) (1) reacts with two [Pd((15)NH(2)(CH(2))(2)(15)NH(2))(NO(3))(2)] in water to form a kinetically stable intermediate, [[Pden](2)[(1,4)(5,8)-peptide]](2), in which two 19-membered metallocyclic rings stabilize two peptide turns. Slow subsequent folding to a thermodynamically more stable two-turn alpha-helix drives the equilibrium to [[Pden](2)[(1,5)(4,8)-peptide]] (3), featuring two 22-membered rings. This transformation from unstructured peptide via turns to an alpha-helix suggests that metal clips might be useful probes for investigating peptide folding.
Human MAIT cell cytolytic effector proteins synergize to overcome carbapenem resistance in Escherichia coli
Publisher: Public Library of Science (PLoS)
Date: 08-06-2020
Mucosal-Associated Invariant T Cell Effector Function Is an Intrinsic Cell Property That Can Be Augmented by the Metabolic Cofactor α-Ketoglutarate
Publisher: The American Association of Immunologists
Date: 04-2021
Abstract: Mucosal-associated invariant T (MAIT) cells are an innate-like population of unconventional T cells that respond rapidly to microbial metabolite Ags or cytokine stimulation. Because of this reactivity and surface expression of CD45RO+, CD45RA−, and CD127+, they are described as effector memory cells. Yet, there is heterogeneity in MAIT cell effector response. It is unclear what factors control MAIT cell effector capacity, whether it is fixed or can be modified and if this differs based on whether activation is TCR dependent or independent. To address this, we have taken a systematic approach to examine human MAIT cell effector capacity across healthy in iduals in response to ligand and cytokine stimulation. We demonstrate the heterogenous nature of MAIT cell effector capacity and that the ability to produce an effector response is not directly attributable to TCR clonotype or coreceptor expression. Global gene transcription analysis revealed that the MAIT cell effector capacity produced in response to TCR stimulation is associated with increased expression of the epigenetic regulator lysine demethylase 6B (KDM6B). Addition of a KDM6B inhibitor did not alter MAIT cell effector function to Ag or cytokine stimulation. However, addition of the KDM6B cofactor α-ketoglutarate greatly enhanced MAIT cell effector capacity to TCR-dependent stimulation in a partially KDM6B-dependent manner. These results demonstrate that the TCR-dependent effector response of MAIT cells is epigenetically regulated and dependent on the availability of metabolic cofactors.
Erratum: Selective hexapeptide agonists and antagonists for human complement C3a receptor (Journal of Medicinal Chemistry (2010) 53 (4938) DOI: 10.1021/jm1003705)
Publisher: American Chemical Society (ACS)
Date: 29-10-2010
DOI: 10.1021/JM1013314
Simple cis-epoxide-based inhibitors of HIV-1 protease
Publisher: Elsevier BV
Date: 11-1997
Rv2969c, essential for optimal growth inMycobacterium tuberculosis, is a DsbA-like enzyme that interacts with VKOR-derived peptides and has atypical features of DsbA-like disulfide oxidases
Publisher: International Union of Crystallography (IUCr)
Date: 20-09-2013
DOI: 10.1107/S0907444913017800
Abstract: The bacterial disulfide machinery is an attractive molecular target for developing new antibacterials because it is required for the production of multiple virulence factors. The archetypal disulfide oxidase proteins in Escherichia coli (Ec) are DsbA and DsbB, which together form a functional unit: DsbA introduces disulfides into folding proteins and DsbB reoxidizes DsbA to maintain it in the active form. In Mycobacterium tuberculosis (Mtb), no DsbB homologue is encoded but a functionally similar but structurally ergent protein, MtbVKOR, has been identified. Here, the Mtb protein Rv2969c is investigated and it is shown that it is the DsbA-like partner protein of MtbVKOR. It is found that it has the characteristic redox features of a DsbA-like protein: a highly acidic catalytic cysteine, a highly oxidizing potential and a destabilizing active-site disulfide bond. Rv2969c also has peptide-oxidizing activity and recognizes peptide segments derived from the periplasmic loops of MtbVKOR. Unlike the archetypal EcDsbA enzyme, Rv2969c has little or no activity in disulfide-reducing and disulfide-isomerase assays. The crystal structure of Rv2969c reveals a canonical DsbA fold comprising a thioredoxin domain with an embedded helical domain. However, Rv2969c erges considerably from other DsbAs, including having an additional C-terminal helix (H8) that may restrain the mobility of the catalytic helix H1. The enzyme is also characterized by a very shallow hydrophobic binding surface and a negative electrostatic surface potential surrounding the catalytic cysteine. The structure of Rv2969c was also used to model the structure of a paralogous DsbA-like domain of the Ser/Thr protein kinase PknE. Together, these results show that Rv2969c is a DsbA-like protein with unique properties and a limited substrate-binding specificity.
Beta-Strand Mimetics
Publisher: American Chemical Society (ACS)
Date: 04-11-2004
DOI: 10.1021/CR040648K
The genetic and clinical landscape of nanophthalmos and posterior microphthalmos in an Australian cohort
Publisher: Wiley
Date: 05-03-2020
DOI: 10.1111/CGE.13722
Solution structure of amyloid β-peptide(1-40) in a water-micelle environment. Is the membrane-spanning domain where we think it is?
Publisher: American Chemical Society (ACS)
Date: 16-07-1998
DOI: 10.1021/BI972979F
Differential effects of selective HDAC inhibitors on macrophage inflammatory responses to the Toll-like receptor 4 agonist LPS
Publisher: Oxford University Press (OUP)
Date: 03-03-2010
DOI: 10.1189/JLB.0509363
Abstract: Selective inhibitor studies in macrophages implicate class II HDAC enzymes in TLR-mediated inflammatory pathways and class I HDACs as negative regulators. Broad-spectrum inhibitors of HDACs are therapeutic in many inflammatory disease models but exacerbated disease in a mouse model of atherosclerosis. HDAC inhibitors have anti- and proinflammatory effects on macrophages in vitro. We report here that several broad-spectrum HDAC inhibitors, including TSA and SAHA, suppressed the LPS-induced mRNA expression of the proinflammatory mediators Edn-1, Ccl-7/MCP-3, and Il-12p40 but lified the expression of the proatherogenic factors Cox-2 and Pai-1/serpine1 in primary mouse BMM. Similar effects were also apparent in LPS-stimulated TEPM and HMDM. The pro- and anti-inflammatory effects of TSA were separable over a concentration range, implying that in idual HDACs have differential effects on macrophage inflammatory responses. The HDAC1-selective inhibitor, MS-275, retained proinflammatory effects ( lification of LPS-induced expression of Cox-2 and Pai-1 in BMM) but suppressed only some inflammatory responses. In contrast, 17a (a reportedly HDAC6-selective inhibitor) retained anti-inflammatory but not proinflammatory properties. Despite this, HDAC6−/− macrophages showed normal LPS-induced expression of HDAC-dependent inflammatory genes, arguing that the anti-inflammatory effects of 17a are not a result of inhibition of HDAC6 alone. Thus, 17a provides a tool to identify in idual HDACs with proinflammatory properties.
Mutagenesis of the West Nile virus NS2B cofactor domain reveals two regions essential for protease activity
Publisher: Microbiology Society
Date: 04-2008
Abstract: The flavivirus NS2B/NS3 protease has received considerable attention as a target for the development of antiviral compounds. While substrate based inhibitors have been the primary focus to date, an approach focussing on NS2B cofactor displacement could prove to be an effective alternative. To understand better the role of the NS2B cofactor in protease activation, we conducted an alanine mutagenesis screen throughout the 42-residue central cofactor domain (NS2B 51–92 ) of West Nile virus (WNV). Two sites critical for proteolytic activity were identified (NS2B 59–62 and NS2B 75–87 ), where the majority of substitutions were found to significantly decrease proteolytic activity of a recombinant WNV NS2B/NS3 protease. These findings provide mechanistic insights into the structural and functional role that the cofactor may play in the substrate-bound and free protease complexes as well as providing novel sites for targeting new antiviral inhibitors.
Pathway‐selective antagonism of proteinase activated receptor 2
Publisher: Wiley
Date: 02-07-2014
DOI: 10.1111/BPH.12757
Protease inhibitors in the clinic.
Publisher: Bentham Science Publishers Ltd.
Date: 2005
Abstract: This review describes the clinical status (based on available information) of experimental drugs that inhibit enzymes called proteases, or more precisely a sub-class of proteases called peptidases that catalyse the hydrolysis of polypeptide main chain amide bonds. These peptidases are classified by the key catalytic residue in the active site of the enzyme that effects hydrolysis, namely aspartic, serine, cysteine, metallo or threonine proteases. In this review we show structures for 108 inhibitors of these enzymes and update the clinical disposition of over 100 inhibitors that have been considered worthy enough by pharmaceutical, biotechnology or academic researchers and their financial backers to be trialed in humans as prospective medicines. We outline some of their chemical and pharmacological characteristics and compare the current status of protease inhibitors in the clinic with what was observed about 5 years ago (Leung et al, J. Med. Chem. 2000, 43, 305-341). We assess the progress of protease inhibitors into man, predict their futures, and outline some of the hurdles that have been overcome and that still remain for this promising class of new therapeutic agents.
Anti-tumour activity in vitro and in vivo of selective differentiating agents containing hydroxamate
Publisher: Springer Science and Business Media LLC
Date: 28-05-1999
Modulating human proteinase activated receptor 2 with a novel antagonist (GB88) and agonist (GB110)
Publisher: Wiley
Date: 10-02-2012
Benzylamide antagonists of protease activated receptor 2 with anti-inflammatory activity
Publisher: Elsevier BV
Date: 02-2016
DOI: 10.1016/J.BMCL.2015.12.048
Abstract: Activation of protease activated receptor 2 (PAR2) has been implicated in inflammatory and metabolic disorders and its inhibition may yield novel therapeutics. Here, we report a series of PAR2 antagonists based on C-terminal capping of 5-isoxazolyl-L-cyclohexylalanine-L-isoleucine, with benzylamine analogues being effective new PAR2 antagonists. 5-Isoxazolyl-L-cyclohexylalanine-L-isoleucine-2-methoxybenzylamine (10) inhibited PAR2-, but not PAR1-, induced release of Ca(2+) (IC50 0.5 μM) in human colon cells, IL-6 and TNFα secretion (IC50 1-5 μM) from human kidney cells, and was anti-inflammatory in acute rat paw inflammation (ED50 5 mg/kg sc). These findings show that new benzylamide antagonists of PAR2 have anti-inflammatory activity.
The Role of the N-terminal Domain of the Complement Fragment Receptor C5L2 in Ligand Binding
Publisher: Elsevier BV
Date: 02-2007
A peculiar toxicity manifested by platinum(II)amines in rats: Gastric distension after intraperitoneal administration
Publisher: Elsevier BV
Date: 04-1981
DOI: 10.1016/0009-2797(81)90066-1
Abstract: Metoclopramide i.p. reduces the gastric distension consistently seen in rats given cisplatin i.p. at effective immunosuppressant doses (6 mg/kg). Many other immunosuppressant/oncolytic platinum amines also engendered gastric distension but certain dimers and 1,2-cyclohexanediaminoplatinum (II) compounds did not. This phenomenon appears to be due to paralysis of gastric emptying (without appetite suppression).
The intracellular pathway for the presentation of vitamin B–related antigens by the antigen-presenting molecule MR1
Publisher: Springer Science and Business Media LLC
Date: 04-04-2016
DOI: 10.1038/NI.3416
Abstract: The antigen-presenting molecule MR1 presents vitamin B-related antigens (VitB antigens) to mucosal-associated invariant T (MAIT) cells through an uncharacterized pathway. We show that MR1, unlike other antigen-presenting molecules, does not constitutively present self-ligands. In the steady state it accumulates in a ligand-receptive conformation within the endoplasmic reticulum. VitB antigens reach this location and form a Schiff base with MR1, triggering a 'molecular switch' that allows MR1-VitB antigen complexes to traffic to the plasma membrane. These complexes are endocytosed with kinetics independent of the affinity of the MR1-ligand interaction and are degraded intracellularly, although some MR1 molecules acquire new ligands during passage through endosomes and recycle back to the surface. MR1 antigen presentation is characterized by a rapid 'off-on-off' mechanism that is strictly dependent on antigen availability.
Single turn peptide alpha helices with exceptional stability in water
Publisher: American Chemical Society (ACS)
Date: 12-02-2005
DOI: 10.1021/JA0456003
Abstract: Cyclic pentapeptides are not known to exist in alpha-helical conformations. CD and NMR spectra show that specific 20-membered cyclic pentapeptides, Ac-(cyclo-1,5) [KxxxD]-NH(2) and Ac-(cyclo-2,6)-R[KxxxD]-NH(2), are highly alpha-helical structures in water and independent of concentration, TFE, denaturants, and proteases. These are the smallest alpha-helical peptides in water.
Matching cavities in G protein-coupled receptors to infer ligand-binding sites
Publisher: American Chemical Society (ACS)
Date: 30-04-2012
DOI: 10.1021/CI2005498
Abstract: To understand the activity and cross reactivity of ligands and G protein-coupled receptors, we take stock of relevant existing receptor mutation, sequence, and structural data to develop a statistically robust and transparent scoring system. Our method evaluates the viability of binding of any ligand for any GPCR sequence of amino acids. This enabled us to explore the binding repertoire of both receptors and ligands, relying solely on correlations between carefully identified receptor features and without requiring any chemical information about ligands. This study suggests that sequence similarity at specific binding pockets can predict relative affinity of ligands enabling recovery of over 80% of known ligands for a withheld receptor and almost 80% of known receptors for a ligand. The method enables qualitative prediction of ligand binding for all nonredundant human G protein-coupled receptors.
Total Synthesis of Mycobacterium tuberculosis Dideoxymycobactin-838 and Stereoisomers: Diverse CD1a-Restricted T Cells Display a Common Hierarchy of Lipopeptide Recognition
Publisher: Wiley
Date: 18-01-2017
α-Turn Mimetics: Short Peptide α-Helices Composed of Cyclic Metallopentapeptide Modules
Publisher: American Chemical Society (ACS)
Date: 26-03-2004
DOI: 10.1021/JA037980I
Abstract: Alpha-Helices are key structural components of proteins and important recognition motifs in biology. Short peptides (<or=15 residues) corresponding to these helical sequences are rarely helical away from their stabilizing protein environments. New techniques for stabilizing short peptide helices could be valuable for studying protein folding, modeling proteins, creating artificial proteins, and may aid the design of inhibitors or mimics of protein function. This study reports the facile incorporation of 3- and 4-alpha turns in 10-15 residue peptides through formation in situ of multiple cyclic metallopeptide modules [Pd(en)(H*XXXH*)](2+). The nonhelical peptides Ac-H*ELTH*H*VTDH*-NH(2) (1), Ac-H*ELTH*AVTDYH*ELTH*-NH(2) (2), and Ac-H*AAAH*HELTH*H*VTDH*-NH(2) (3) (H is histidine-methylated at imidazole-N3) react in N,N-dimethylformamide (DMF) or water with 2, 2, and 3 molar equivalents, respectively, of [Pd(en)(NO(3))(2)] to form exclusively [Pd(2)(en)(2)(Ac-H*ELTH*H*VTDH*-NH(2))](4+) (4), [Pd(2)(en)(2)(Ac-H*ELTH*AVTDYH*ELTH*-NH(2))](4+) (5), and [Pd(3)(en)(3)(Ac-H*AAAH*HELTH*H*VTDH*-NH(2))](6+) (6), characterized by mass spectrometry, 1D and 2D (1)H- and 1D (15)N-NMR spectroscopy. Despite the presence of multiple histidines and other possible metal-binding residues in these peptides, 2D (1)H NMR spectra reveal that Pd(en)(2+) is remarkably specific in coordinating to imidazole-N1 of only (i, i + 4) pairs of histidines (i.e., only those separated by three amino acids), resulting in 4-6 made up of cyclic metallopentapeptide modules ([Pd(en)(H*XXXH*)](2+))(n), n = 2, 2, 3, respectively, each cycle being a 22-membered ring. We have previously shown that a single metallopentapeptide can nucleate alpha-helicity (Kelso et al., Angew. Chem., Int. Ed. 2003, 42, 421-424.). We now demonstrate its use as an alpha-turn-mimicking module for the facile conversion of unstructured short peptides into helices of macrocycles and provide 1D and 2D NMR spectroscopic data, structure calculations via XPLOR and NMR analysis of molecular flexibility in solution (NAMFIS), and CD spectra in support of the alpha-helical nature of these monomeric metallopeptides in solution.
Function, structure and therapeutic potential of complement C5a receptors
Publisher: Wiley
Date: 10-2007
Organic Azide Inhibitors of Cysteine Proteases [J. Am. Chem. Soc. 2006, 128, 12396−12397].
Publisher: American Chemical Society (ACS)
Date: 11-07-2007
DOI: 10.1021/JA076897I
Metal Clips That Induce Unstructured Pentapeptides To Be α-Helical In Water
Publisher: American Chemical Society (ACS)
Date: 05-03-2009
DOI: 10.1021/JA900047W
Abstract: Short peptides corresponding to protein helices do not form thermodynamically stable helical structures in water, a solvent that strongly competes for hydrogen-bonding amides of the peptide backbone. Metalloproteins often feature metal ions coordinated to amino acids within hydrogen-bonded helical regions of protein structure, so there is a prospect of metals stabilizing or inducing helical structures in short peptides. However, this has only previously been observed in nonaqueous solvents or under strongly helix-favoring conditions in water. Here cis-[Ru(NH(3))(4)(solvent)(2)](2+) and [Pd(en)(solvent)(2)](2+) are compared in water for their capacity as metal clips to induce alpha-helicity in completely unstructured peptides as short as five residues, Ac-HARAH-NH(2) and Ac-MARAM-NH(2). More alpha-helicity was observed for the latter pentapeptide and, when chelated to ruthenium, it showed the greatest alpha-helicity yet reported for a short metallopeptide in water (approximately 80%). Helicity was clearly induced rather than stabilized, and the two methionines were 10(13)-fold more effective than two histidines in stabilizing the lower oxidation state Ru(II) over Ru(III). The study identifies key factors that influence stability of an alpha-helical turn in water, suggests metal ions as tools for peptide folding, and raises an intriguing possibility of transiently coordinated metal ions playing important roles in native folding of polypeptides in water.
cis-Platinum(II) amine complexes: Some structure-activity relationships for immunosuppressive, nephrotoxic and gastrointestinal (side) effects in rats
Publisher: Elsevier BV
Date: 07-1980
DOI: 10.1016/0009-2797(80)90144-1
Abstract: A local graft-versus-host reaction was established to elicit lymphoid hypertrophy in F1 hybrid PVG X Lew rats. cis-Di(amine)platinum(II) complexes were given i.p. on days 1--4 in ided doses. Overnight proteinuria and measurements of renal hypertrophy on day 5 reflected the nephrotoxicity of the test compound. Stomach weights indicated the peculiar effect on pyloric stasis causing gastric distension. Weights of thymus' and spleens together with lymph-nodes showed the lymphodepressant/immunosuppressive properties of platinum compounds. Structure activity relationships for immunosuppressant, nephrotoxic and gastric-distending activities were investigated with: (a) cis-diaquo, cis-hydroxyaquo- and cis-dichlorodi(amine)platinum(II) complexes (b) dinuclear mu-dihydroxo-bridged di(amine)platinum(II) complexes (c) carboxylatodi(amine)platinum(II) complexes. Nephrotoxicity was minimised (with retention of immunosuppressant activity) by (a) the use of certain N-substituted amines e.g. Dach, Me4en (b) co-administration of selected adjuncts e.g. citrate, salicylate (c) auxiliary treatment with a penicillin mixture (Triplopen). In vitro effects of some platinum(II) compounds on isolated rat kidney tubules were also investigated.
A new dinuclear amine-cobalt(III) complex containing two bridging amide ions
Publisher: Elsevier BV
Date: 07-1993
Amyloid peptides and proteins in review
Publisher: Springer Berlin Heidelberg
Date: 2007
Abstract: Amyloids are filamentous protein deposits ranging in size from nanometres to microns and composed of aggregated peptide beta-sheets formed from parallel or anti-parallel alignments of peptide beta-strands. Amyloid-forming proteins have attracted a great deal of recent attention because of their association with over 30 diseases, notably neurodegenerative conditions like Alzheimer's, Huntington's, Parkinson's, Creutzfeldt-Jacob and prion disorders, but also systemic diseases such as amyotrophic lateral sclerosis (Lou Gehrig's disease) and type II diabetes. These diseases are all thought to involve important conformational changes in proteins, sometimes termed misfolding, that usually produce beta-sheet structures with a strong tendency to aggregate into water-insoluble fibrous polymers. Reasons for such conformational changes in vivo are still unclear. Intermediate aggregated state(s), rather than precipitated insoluble polymeric aggregates, have recently been implicated in cellular toxicity and may be the source of aberrant pathology in amyloid diseases. Numerous in vitro studies of short and medium length peptides that form amyloids have provided some clues to amyloid formation, with an alpha-helix to beta-sheet folding transition sometimes implicated as an intermediary step leading to amyloid formation. More recently, quite a few non-pathological amyloidogenic proteins have also been identified and physiological properties have been ascribed, challenging previous implications that amyloids were always disease causing. This article summarises a great deal of current knowledge on the occurrence, structure, folding pathways, chemistry and biology associated with amyloidogenic peptides and proteins and highlights some key factors that have been found to influence amyloidogenesis.
A Potent Antagonist of Protease-Activated Receptor 2 That Inhibits Multiple Signaling Functions in Human Cancer Cells
Publisher: American Society for Pharmacology & Experimental Therapeutics (ASPET)
Date: 20-12-2017
Abstract: Protease-activated receptor 2 (PAR2) is a cell surface protein linked to G-protein dependent and independent intracellular signaling pathways that produce a wide range of physiological responses, including those related to metabolism, inflammation, pain, and cancer. Certain proteases, peptides, and nonpeptides are known to potently activate PAR2. However, no effective potent PAR2 antagonists have been reported yet despite their anticipated therapeutic potential. This study investigates antagonism of key PAR2-dependent signaling properties and functions by the imidazopyridazine compound I-191 (4-(8-(
N-(2-Aminophenyl)-benzamide Inhibitors of Class I HDAC Enzymes with Antiproliferative and Antifibrotic Activity
Publisher: American Chemical Society (ACS)
Date: 05-10-2023
Protein a-Turns Recreated in Structurally Stable Small Molecules
Publisher: Wiley
Date: 29-09-2011
Comparative gene expression profiling of P. falciparum malaria parasites exposed to three different histone deacetylase inhibitors
Publisher: Public Library of Science (PLoS)
Date: 27-02-2012
Biased signalling and proteinase‐activated receptors (PAR s): targeting inflammatory disease
Publisher: Wiley
Date: 27-02-2014
DOI: 10.1111/BPH.12544
Erratum to Profiling the anti-protozoal activity of anti-cancer HDAC inhibitors against Plasmodium and Trypanosoma parasites [Int. J. Parasitol. Drugs Drug Res. 5 (2015) 117-126].
Publisher: Elsevier BV
Date: 12-2016
Small peptides do not inhibit human non-pancreatic secretory phospholipase-A2 (type IIA)
Publisher: Elsevier BV
Date: 08-2000
Electrophilic Helical Peptides That Bond Covalently, Irreversibly, and Selectively in a Protein–Protein Interaction Site
Publisher: American Chemical Society (ACS)
Date: 17-11-2016
Helical structure in cyclic peptides: effect of N-methyl amides versus esters
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2CC05092G
Abstract: Cyclic peptides with esters but not N -methyl amides are the smallest known alpha helices in water and can enter cells.
Comparing sixteen scoring functions for predicting biological activities of ligands for protein targets
Publisher: Elsevier BV
Date: 04-2015
DOI: 10.1016/J.JMGM.2015.01.009
Abstract: Accurately predicting relative binding affinities and biological potencies for ligands that interact with proteins remains a significant challenge for computational chemists. Most evaluations of docking and scoring algorithms have focused on enhancing ligand affinity for a protein by optimizing docking poses and enrichment factors during virtual screening. However, there is still relatively limited information on the accuracy of commercially available docking and scoring software programs for correctly predicting binding affinities and biological activities of structurally related inhibitors of different enzyme classes. Presented here is a comparative evaluation of eight molecular docking programs (Autodock Vina, Fitted, FlexX, Fred, Glide, GOLD, LibDock, MolDock) using sixteen docking and scoring functions to predict the rank-order activity of different ligand series for six pharmacologically important protein and enzyme targets (Factor Xa, Cdk2 kinase, Aurora A kinase, COX-2, pla2g2a, β Estrogen receptor). Use of Fitted gave an excellent correlation (Pearson 0.86, Spearman 0.91) between predicted and experimental binding only for Cdk2 kinase inhibitors. FlexX and GOLDScore produced good correlations (Pearson>0.6) for hydrophilic targets such as Factor Xa, Cdk2 kinase and Aurora A kinase. By contrast, pla2g2a and COX-2 emerged as difficult targets for scoring functions to predict ligand activities. Although possessing a high hydrophobicity in its binding site, β Estrogen receptor produced reasonable correlations using LibDock (Pearson 0.75, Spearman 0.68). These findings can assist medicinal chemists to better match scoring functions with ligand-target systems for hit-to-lead optimization using computer-aided drug design approaches.
Truncated and Helix-Constrained Peptides with High Affinity and Specificity for the cFos Coiled-Coil of AP-1
Publisher: Public Library of Science (PLoS)
Date: 27-03-2013
Organic Azide Inhibitors of Cysteine Proteases
Publisher: American Chemical Society (ACS)
Date: 09-2006
DOI: 10.1021/JA0637649
Abstract: Cysteine proteases are crucial regulatory enzymes in human physiology and disease. Inhibitors are usually designed with reactive electrophiles to covalently bond to the catalytic cysteinyl sulfur, and consequently they also indiscriminately interact with biological thiolates and other nucleophiles, leading to toxic side effects in vivo. Here we describe an alternative to using reactive electrophiles, demonstrating the use of a much less reactive azidomethylene substituent (-CH2-N3) that confers potent inhibition of cysteine proteases. This new approach resulted in potent, reversible, competitive inhibitors of caspase-1 (IC50 < 10 nM), with significant advantages over aldehydes such as high stability in vitro to thiols (10 mM dithiothreitol (pH 7.2), 20 mM glutathione (pH 7.2, 9, 11)) and aqueous media, as well as some highly desirable druglike features. It was also demonstrated that azides can be incorporated into inhibitors of other caspases (e.g. 3, 8) and cathepsins (e.g. K, S, B), indicating the versatility of this valuable new approach to cysteine protease inhibition.
Platinum drugs: Combined anti-lymphoproliferative and nephrotoxicity assay in rats
Publisher: Springer Science and Business Media LLC
Date: 11-1980
DOI: 10.1007/BF00255269
Antagonism of Protease-Activated Receptor 2 Protects against Experimental Colitis
Publisher: American Society for Pharmacology & Experimental Therapeutics (ASPET)
Date: 25-10-2011
Abstract: Many trypsin-like serine proteases such as β-tryptase are involved in the pathogenesis of colitis and inflammatory bowel diseases. Inhibitors of in idual proteases show limited efficacy in treating such conditions, but also probably disrupt digestive and defensive functions of proteases. Here, we investigate whether masking their common target, protease-activated receptor 2 (PAR2), is an effective therapeutic strategy for treating acute and chronic experimental colitis in rats. A novel PAR2 antagonist (5-isoxazoyl-Cha-Ile-spiro[indene-1,4'-piperidine] GB88) was evaluated for the blockade of intracellular calcium release in colonocytes and anti-inflammatory activity in acute (PAR2 agonist-induced) versus chronic [2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced] models of colitis in Wistar rats. Disease progression (disease activity index, weight loss, and mortality) and postmortem colonic histopathology (inflammation, bowel wall thickness, and myeloperoxidase) were measured. PAR2 and tryptase colocalization were investigated by using immunohistochemistry. GB88 was a more potent antagonist of PAR2 activation in colonocytes than another reported compound, N¹-3-methylbutyryl-N⁴-6-aminohexanoyl-piperazine (ENMD-1068) (IC₅₀ 8 μM versus 5 mM). Acute colonic inflammation induced in rats by the PAR2 agonist SLIGRL-NH₂ was inhibited by oral administration of GB88 (10 mg/kg) with markedly reduced edema, mucin depletion, PAR2 receptor internalization, and mastocytosis. Chronic TNBS-induced colitis in rats was ameliorated by GB88 (10 mg/kg/day p.o.), which reduced mortality and pathology (including colon obstruction, ulceration, wall thickness, and myeloperoxidase release) more effectively than the clinically used drug sulfasalazine (100 mg/kg/day p.o.). These disease-modifying properties for the PAR2 antagonist in both acute and chronic experimental colitis strongly support a pathogenic role for PAR2 and PAR2-activating proteases and therapeutic potential for PAR2 antagonism in inflammatory diseases of the colon.
Lysine Acetylation in Sexual Stage Malaria Parasites Is a Target for Antimalarial Small Molecules
Publisher: American Society for Microbiology
Date: 07-2014
DOI: 10.1128/AAC.02721-13
Abstract: Therapies to prevent transmission of malaria parasites to the mosquito vector are a vital part of the global malaria elimination agenda. Primaquine is currently the only drug with such activity however, its use is limited by side effects. The development of transmission-blocking strategies requires an understanding of sexual stage malaria parasite (gametocyte) biology and the identification of new drug leads. Lysine acetylation is an important posttranslational modification involved in regulating eukaryotic gene expression and other essential processes. Interfering with this process with histone deacetylase (HDAC) inhibitors is a validated strategy for cancer and other diseases, including asexual stage malaria parasites. Here we confirm the expression of at least one HDAC protein in Plasmodium falciparum gametocytes and show that histone and nonhistone protein acetylation occurs in this life cycle stage. The activity of the canonical HDAC inhibitors trichostatin A (TSA) and suberoylanilide hydroxamic acid (SAHA Vorinostat) and a panel of novel HDAC inhibitors on early/late-stage gametocytes and on gamete formation was examined. Several compounds displayed early/late-stage gametocytocidal activity, with TSA being the most potent (50% inhibitory concentration, 70 to 90 nM). In contrast, no inhibitory activity was observed in P. falciparum gametocyte exflagellation experiments. Gametocytocidal HDAC inhibitors caused hyperacetylation of gametocyte histones, consistent with a mode of action targeting HDAC activity. Our data identify HDAC inhibitors as being among a limited number of compounds that target both asexual and sexual stage malaria parasites, making them a potential new starting point for gametocytocidal drug leads and valuable tools for dissecting gametocyte biology.
Complement c5a receptor facilitates cancer metastasis by altering t-cell responses in the metastatic niche
Publisher: American Association for Cancer Research (AACR)
Date: 30-06-2014
DOI: 10.1158/0008-5472.CAN-14-0157
Abstract: The impact of complement on cancer metastasis has not been well studied. In this report, we demonstrate in a preclinical mouse model of breast cancer that the complement anaphylatoxin C5a receptor (C5aR) facilitates metastasis by suppressing effector CD8+ and CD4+ T-cell responses in the lungs. Mechanisms of this suppression involve recruitment of immature myeloid cells to the lungs and regulation of TGFβ and IL10 production in these cells. TGFβ and IL10 favored generation of T regulatory cells (Treg) and Th2-oriented responses that rendered CD8+ T cells dysfunctional. Importantly, pharmacologic blockade of C5aR or its genetic ablation in C5aR-deficient mice were sufficient to reduce lung metastases. Depletion of CD8+ T cells abolished this beneficial effect, suggesting that CD8+ T cells were responsible for the effects of C5aR inhibition. In contrast to previous findings, we observed that C5aR signaling promoted Treg generation and suppressed T-cell responses in organs where metastases arose. Overall, our findings indicated that the immunomodulatory functions of C5aR are highly context dependent. Furthermore, they offered proof-of-concept for complement-based immunotherapies to prevent or reduce cancer metastasis. Cancer Res 74(13) 3454–65. ©2014 AACR.
Identification of phenotypically and functionally heterogeneous mouse mucosal-associated invariant T cells using MR1 tetramers
Publisher: Rockefeller University Press
Date: 22-06-2015
DOI: 10.1084/JEM.20142110
Abstract: Studies on the biology of mucosal-associated invariant T cells (MAIT cells) in mice have been h ered by a lack of specific reagents. Using MR1-antigen (Ag) tetramers that specifically bind to the MR1-restricted MAIT T cell receptors (TCRs), we demonstrate that MAIT cells are detectable in a broad range of tissues in C57BL/6 and BALB/c mice. These cells include CD4−CD8−, CD4−CD8+, and CD4+CD8− subsets, and their frequency varies in a tissue- and strain-specific manner. Mouse MAIT cells have a CD44hiCD62Llo memory phenotype and produce high levels of IL-17A, whereas other cytokines, including IFN-γ, IL-4, IL-10, IL-13, and GM-CSF, are produced at low to moderate levels. Consistent with high IL-17A production, most MAIT cells express high levels of retinoic acid–related orphan receptor γt (RORγt), whereas RORγtlo MAIT cells predominantly express T-bet and produce IFN-γ. Most MAIT cells express the promyelocytic leukemia zinc finger (PLZF) transcription factor, and their development is largely PLZF dependent. These observations contrast with previous reports that MAIT cells from Vα19 TCR transgenic mice are PLZF− and express a naive CD44lo phenotype. Accordingly, MAIT cells from normal mice more closely resemble human MAIT cells than previously appreciated, and this provides the foundation for further investigations of these cells in health and disease.
QSAR Classification Models for Prediction of Hydroxamate Histone Deacetylase Inhibitor Activity against Malaria Parasites
Publisher: American Chemical Society (ACS)
Date: 05-01-2022
DOI: 10.1021/ACSINFECDIS.1C00355
Abstract: Malaria, caused by
Orally Absorbed Cyclic Peptides
Publisher: American Chemical Society (ACS)
Date: 25-05-2017
DOI: 10.1021/ACS.CHEMREV.6B00838
Abstract: Peptides and proteins are not orally bioavailable in mammals, although a few peptides are intestinally absorbed in small amounts. Polypeptides are generally too large and polar to passively diffuse through lipid membranes, while most known active transport mechanisms facilitate cell uptake of only very small peptides. Systematic evaluations of peptides with molecular weights above 500 Da are needed to identify parameters that influence oral bioavailability. Here we describe 125 cyclic peptides containing four to thirty-seven amino acids that are orally absorbed by mammals. Cyclization minimizes degradation in the gut, blood, and tissues by removing cleavable N- and C-termini and by shielding components from metabolic enzymes. Cyclization also folds peptides into bioactive conformations that determine exposure of polar atoms to solvation by water and lipids and therefore can influence oral bioavailability. Key chemical properties thought to influence oral absorption and bioavailability are analyzed, including molecular weight, octanol-water partitioning, hydrogen bond donors/acceptors, rotatable bonds, and polar surface area. The cyclic peptides violated to different degrees all of the limits traditionally considered to be important for oral bioavailability of drug-like small molecules, although fewer hydrogen bond donors and reduced flexibility generally favored oral absorption.
Wollamide Cyclic Hexapeptides Synergize with Established and New Tuberculosis Antibiotics in Targeting Mycobacterium tuberculosis
Publisher: American Society for Microbiology
Date: 17-08-2023
DOI: 10.1128/SPECTRUM.00465-23
Abstract: Tuberculosis (TB) is an infectious disease that affects millions of people globally, with 1.6 million deaths annually. TB treatment requires combinations of multiple different antibiotics for many months, and toxic side effects can occur.
West Nile Virus NS2B/NS3 protease as an antiviral target
Publisher: Bentham Science Publishers Ltd.
Date: 11-2008
DOI: 10.2174/092986708786242804
Abstract: West Nile Virus (WNV) has spread rapidly during the last decade across five continents causing disease and fatalities in humans and mammals. It highlights the serious threat to both our health and the economy posed by viruses crossing species, in this case from migratory birds via mosquitoes to mammals. There is no vaccine or antiviral drug for treating WNV infection. One attractive target for antiviral development is a viral trypsin-like serine protease, encoded by the N-terminal 184 amino acids of NS3, which is only active when tethered to its cofactor, NS2B. This protease, NS2B/NS3pro, cleaves the viral polyprotein to release structural and non-structural viral proteins that are essential in viral replication and assembly of new virus particles. Disruption of this protease activity is lethal for virus replication. The NS3 protein also has other enzymes within its sequence (helicase, nucleoside triphosphatase, RNA triphosphatase), all of which are tightly regulated through localisation within membranous compartments in the infected cell. This review describes the various roles of NS3, focussing on NS2B-NS3 protease and its function and regulation in WNV replication and infection. Current advances towards development of antiviral inhibitors of NS2B/NS3pro are examined along with obstacles to their development as an antiviral therapy.
Potent inhibitors of West Nile Virus NS2B/NS3 protease
Publisher: Figshare
Date: 2019
Chemical Approaches to Modulating Complement-Mediated Diseases
Publisher: American Chemical Society (ACS)
Date: 04-10-2017
DOI: 10.1021/ACS.JMEDCHEM.7B00882
Abstract: Numerous diseases are driven by chronic inflammation, placing major burdens on our health systems. Controlling inflammation is an important preventative and therapeutic goal. Over 40 "Complement" proteins are produced in blood or on cell surfaces through activation of the Complement protein network mainly by infection or injury. These proteins complement immune cells and antibodies to identify, tag, destroy, and eliminate pathogens and infected or damaged cells and repair tissues. If the inflammatory stimulus is not removed by localized acute immune responses, Complement activation may be prolonged or misdirected to healthy cells, and chronic inflammation can lead to inflammatory or autoimmune diseases. The formation, structures, and interplay between Complement proteins are complex, and this has limited our detailed understanding of their roles and importance in physiology and disease. With the availability of new structures for Complement proteins, new knowledge of how they function, and new modulators of Complement-driven signaling, there are also new opportunities to intervene in Complement-mediated disease. Small molecule and peptide-based drug leads, identified as clues for Complement-directed therapeutic development, are assembled here together with the available evidence for their efficacy in cellular and animal models of human inflammatory disease and in some human clinical conditions.
Cyclooligomerization of Thiazole-Containing Tetrapeptides. Symmetrical Macrocycles with up to 76 Amino Acids
Publisher: American Chemical Society (ACS)
Date: 03-1999
DOI: 10.1021/JA983354N
Talarolides Revisited: Cyclic Heptapeptides from an Australian Marine Tunicate-Associated Fungus, Talaromyces sp. CMB-TU011
Publisher: MDPI AG
Date: 11-09-2023
DOI: 10.3390/MD21090487
Tuning Electrostatic and Hydrophobic Surfaces of Aromatic Rings to Enhance Membrane Association and Cell Uptake of Peptides
Publisher: Wiley
Date: 25-05-2022
Abstract: Aromatic groups are key mediators of protein–membrane association at cell surfaces, contributing to hydrophobic effects and π‐membrane interactions. Here we show electrostatic and hydrophobic influences of aromatic ring substituents on membrane affinity and cell uptake of helical, cyclic and cell penetrating peptides. Hydrophobicity is important, but subtle changes in electrostatic surface potential, dipoles and polarizability also enhance association with phospholipid membranes and cell uptake. A combination of fluorine and sulfur substituents on an aromatic ring induces microdipoles that enhance cell uptake of 12‐residue peptide inhibitors of p53‐HDM2 interaction and of cell‐penetrating cyclic peptides. These aromatic motifs can be readily inserted into peptide sidechains to enhance their cell uptake.
Comparative anti-inflammatory activities of antagonists to C3a and C5a receptors in a rat model of intestinal ischaemia/reperfusion injury
Publisher: Wiley
Date: 06-2004
An efficient Fmoc strategy for the rapid synthesis of peptide para-nitroanilides
Publisher: Springer Science and Business Media LLC
Date: 2000
X-ray absorption spectroscopy of cadmium phytochelatin and model systems
Publisher: Elsevier BV
Date: 1999
DOI: 10.1016/S0167-4838(98)00242-8
Abstract: Higher plants, algae and some yeasts respond to potentially toxic heavy metals such as cadmium by synthesizing phytochelatins and related cysteine-rich polypeptides. We have used X-ray absorption spectroscopy to study the nature of cadmium binding in such peptides isolated from maize (Zea mays) exposed to low levels of cadmium, and in two synthetic cadmium-peptide complexes, Cd-(gamma-Glu-Cys)3Gly and Cd-(alpha-Glu-Cys)3Gly. We have used the synthetic ions [Cd(SPh)4]2-, [Cd4(SPh)10]2- and [S4Cd10(SPh)16]4-as crystallographically defined models for the cadmium site. The Cd K-edge extended X-ray absorption fine structure (EXAFS) data, together with the Cd K, LI, LII and LIII near-edge spectra, reveal a predominantly tetrahedral coordination of cadmium by sulfur in both the phytochelatin and synthetic peptide complexes. In particular, the Cd LIII-edge lacks a peak at 3534.9 e V which was found to be prominent for oxygen- or nitrogen-coordinated species. The Cd-S distance in the phytochelatin complex is 2.54 A. The Cd K-edge EXAFS does not show any isolated, well-defined Cd-Cd interactions however, contrary to the conclusion of previous work, their absence is not necessarily indicative of isolated cadmium-thiolate ligation. Evidence from other studies suggests that high static disorder, combined with a large vibrational component, serve to effectively wash out this contribution to the EXAFS. The sulfur K-edge, moreover, shows a low-energy feature both in the phytochelatin and in the synthetic cadmium-peptide complexes which is consistent with sulfide bound in a cluster with cadmium as found for [S4Cd10(SPh)16]4-. This feature strongly suggests the presence of a polynuclear cadmium cluster in maize phytochelatin.
MAIT cells regulate NK cell mediated tumor immunity
Publisher: Research Square Platform LLC
Date: 12-08-2020
DOI: 10.21203/RS.3.RS-50207/V1
Abstract: MR1-restricted mucosal-associated invariant T (MAIT) cells recognize microbial metabolites and play an important role in immunity to infection, however, the role they play in tumor immunity is unclear. Here we show that MAIT cell-deficient mice are more resistant to subcutaneous and lung metastasis B16F10 tumor growth compared to control mice, an effect that was associated with enhanced NK cell numbers and was NK cell-dependent. Analysis of this interplay in cancer patients also revealed that a high expression of a novel MAIT gene signature negatively impacted the prognostic significance of NK cells. Paradoxically, pre-pulsing tumors with MAIT cell antigens, or antigen-mediated MAIT cell activation in vivo, enhanced immunity against B16F10 and E0771 lung tumor metastasis. Furthermore, MAIT cell activation effectively reduced metastatic burden in a more stringent model of established lung metastases in mice. These effects were associated with enhanced NK cell responses and increased expression of both IFNγ-dependent and inflammatory genes in NK cells, which was neutralized by IFNγ blockade. Importantly, activated human MAIT cells also enhanced the function of NK cells isolated from patient tumor s les. These findings provide insight into the contrasting roles that MAIT cells can play in controlling anti-tumor immune responses depending on their activation status, in both mice and humans, and suggest potential therapeutic avenues for exploiting their potential anti-tumor properties for cancer treatment.
Oxygen- and sulfur-bonded thiosulfatopentaamminecobalt(III)
Publisher: Elsevier BV
Date: 1983
Mechanische Verstärkung von Coiled Coils mit Lactam und Histidin‐Metall‐Klammern
Publisher: Wiley
Date: 29-10-2020
Twists or turns: stabilising alpha vs. beta turns in tetrapeptides
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9SC04153B
Abstract: Twisting or turning peptides: ring size and chi angle in side chain cross-linked tetrapeptides together control α- or β-turn structures, which mimic irregular secondary structures in proteins.
Generation and characterization of proteolytically active and highly stable truncated and full-length recombinant West Nile virus NS3
Publisher: Elsevier BV
Date: 05-2007
DOI: 10.1016/J.PEP.2006.10.022
Abstract: West Nile virus is a medically significant emerging pathogen for which there is no effective antiviral therapy. The viral protease encoded by NS2B and NS3 is an attractive target for development of an inhibitor and has been the focus of numerous studies. Most have employed recombinant proteases based on an expression strategy we developed which links the essential hydrophilic cofactor domain within NS2B to the NS3 protease domain by a flexible glycine linker. However, autoproteolysis has been a significant problem associated with this construct. The recently resolved crystal structure of the cofactor bound WNV NS3 protease for ex le, was found to be truncated by 18 residues at its N-terminus. In this study, the autocatalytic cleavage site was identified and removed along with nonessential regions of the glycine linker and cofactor domain. In addition, the optimal size of the NS3 protease was defined. Based on this optimized construct, a recombinant protease incorporating the full length of NS3 was also successfully expressed and purified. Somewhat surprisingly, comparative analysis of the proteolytic activity of this recombinant with that of the protease domain alone revealed little influence of the C-terminal two thirds of NS3 on substrate binding. These modifications have yielded highly stable and constrained recombinant proteases, which are more suitable than existing constructs for both activity and structural studies.
Anti-inflammatory activity of the isoquinoline alkaloid, tetrandrine, against established adjuvant arthritis in rats
Publisher: Springer Science and Business Media LLC
Date: 10-1994
DOI: 10.1007/BF01983477
Proteases universally recognize beta strands in their active sites
Publisher: American Chemical Society (ACS)
Date: 16-02-2005
DOI: 10.1021/CR040669E
Template assembled synthetic proteins (TASPS). Are template size, shape, and directionality important in formation of four-helix bundles?
Publisher: American Chemical Society (ACS)
Date: 04-1998
DOI: 10.1021/JA971951O
Regioselective synthesis of antiparallel loops on a macrocyclic scaffold constrained by oxazoles and thiazoles
Publisher: American Chemical Society (ACS)
Date: 11-09-2002
DOI: 10.1021/OL026463M
Abstract: The regioselective syntheses and structures are reported for two tris-macrocylic compounds, each possessing two antiparallel loops on a macrocyclic scaffold constrained by two oxazoles and two thiazoles. NMR solution structures show the loops projecting from the same face of the macrocycle. Such molecules are shown to be prototypes for mimicking multiple loops of proteins.[structure: see text]
Substrate specificity of recombinant dengue 2 virus NS2B-NS3 protease: Influence of natural and unnatural basic amino acids on hydrolysis of synthetic fluorescent substrates
Publisher: Elsevier BV
Date: 2007
DOI: 10.1016/J.ABB.2006.11.005
Abstract: A recombinant dengue 2 virus NS2B-NS3 protease (NS means non-structural virus protein) was compared with human furin for the capacity to process short peptide substrates corresponding to seven native substrate cleavage sites in the dengue viral polyprotein. Using fluorescence resonance energy transfer peptides to measure kinetics, the processing of these substrates was found to be selective for the Dengue protease. Substrates containing two or three basic amino acids (Arg or Lys) in tandem were found to be the best, with Abz-AKRRSQ-EDDnp being the most efficiently cleaved. The hydrolysis of dipeptide substrates Bz-X-Arg-MCA where X is a non-natural basic amino acid were also kinetically examined, the best substrates containing aliphatic basic amino acids. Our results indicated that proteolytic processing by dengue NS3 protease, tethered to its activating NS2B co-factor, was strongly inhibited by Ca2+ and kosmotropic salts of the Hofmeister's series, and significantly influenced by substrate modifications between S4 and S6'. Incorporation of basic non-natural amino acids in short peptide substrates had significant but differential effects on Km and k(cat), suggesting that further dissection of their influences on substrate affinity might enable the development of effective dengue protease inhibitors.
Helixconstraints and amino acid substitution in GLP-1 increase cAMP and insulin secretion but not beta-arrestin 2 signaling
Publisher: Elsevier BV
Date: 02-2017
DOI: 10.1016/J.EJMECH.2016.10.044
Abstract: Glucagon-like peptide (GLP-1) is an endogenous hormone that induces insulin secretion from pancreatic islets and modified forms are used to treat diabetes mellitus type 2. Understanding how GLP-1 interacts with its receptor (GLP-1R) can potentially lead to more effective drugs. Modeling and NMR studies of the N-terminus of GLP-1 suggest a β-turn between residues Glu9-Phe12 and a kinked alpha helix between Val16-Gly37. N-terminal turn constraints attenuated binding affinity and activity (compounds 1-8). Lys-Asp (i, i+4) crosslinks in the middle and at the C-terminus increased alpha helicity and cAMP stimulation without much effect on binding affinity or beta-arrestin 2 recruitment (compounds 9-18). Strategic positioning of helix-inducing constraints and amino acid substitutions (Tyr16, Ala22) increased peptide helicity and produced ten-fold higher cAMP potency (compounds 19-28) over GLP-1(7-37)-NH
Hookworm Aspartic Protease,Na‐APR‐2, Cleaves Human Hemoglobin and Serum Proteins in a Host‐Specific Fashion
Publisher: Oxford University Press (OUP)
Date: 02-2003
DOI: 10.1086/367708
Abstract: Hookworms are voracious blood-feeders. The cloning and functional expression of an aspartic protease, Na-APR-2, from the human hookworm Necator americanus are described here. Na-APR-2 is more similar to a family of nematode-specific, aspartic proteases than it is to cathepsin D or pepsin, and the term "nemepsins" for members of this family of nematode-specific hydrolases is proposed. Na-apr-2 mRNA was detected in blood-feeding, developmental stages only of N. americanus, and the protease was expressed in the intestinal lumen, hids, and excretory glands. Recombinant Na-APR-2 cleaved human hemoglobin (Hb) and serum proteins almost twice as efficiently as the orthologous substrates from the nonpermissive dog host. Moreover, only 25% of the Na-APR-2 cleavage sites within human Hb were shared with those generated by the related N. americanus cathepsin D, Na-APR-1. Antiserum against Na-APR-2 inhibited migration of 50% of third-stage N. americanus larvae through skin, which suggests that aspartic proteases might be effective vaccines against human hookworm disease.
Glucuronic acid as a helix-inducing linker in short peptides
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C7CC09785A
Abstract: The first ex le of a carbohydrate linker that stabilises an α-helical peptide.
Small Molecular Probes for G-Protein-Coupled C5a Receptors: Conformationally Constrained Antagonists Derived from the C Terminus of the Human Plasma Protein C5a
Publisher: American Chemical Society (ACS)
Date: 08-1998
DOI: 10.1021/JM9800651
Connecting Hydrophobic Surfaces in Cyclic Peptides Increases Membrane Permeability
Publisher: Wiley
Date: 04-03-2021
Synthesis of the Thiazole–Thiazoline Fragment of Largazole Analogues
Publisher: American Chemical Society (ACS)
Date: 08-11-2011
DOI: 10.1021/JO201675R
Abstract: The thiazole-thiazoline fragment of the marine natural product largazole, a potent histone deacetylase 1 inhibitor, has been synthesized in five steps. The methodology provides rapid access to thiazole-4-carbonitrile, thiazole-4-carbimidate, thiazole-oxazoline, and other thiazole-thiazoline derivatives that are important intermediates in the total synthesis of many natural products with important biological properties.
Oxazole-Benzenesulfonamide Derivatives Inhibit HIV-1 Reverse Transcriptase Interaction with Cellular eEF1A and Reduce Viral Replication
Publisher: American Society for Microbiology
Date: 15-06-2019
DOI: 10.1128/JVI.00239-19
Abstract: Antiretroviral drugs protect many HIV-positive people, but their success can be compromised by drug-resistant strains. To combat these strains, the development of new classes of HIV-1 inhibitors is essential and a priority in the field. In this study, we identified small molecules that bind directly to HIV-1 reverse transcriptase (RT) and inhibit its interaction with cellular eEF1A, an interaction which we have previously identified as crucial for HIV-1 replication. These compounds inhibit intracellular HIV-1 reverse transcription and replication of WT HIV-1, as well as HIV-1 mutants that are resistant to current RT inhibitors. A novel mechanism of action involving inhibition of the HIV-1 RT-eEF1A interaction is an important finding and a potential new way to combat drug-resistant HIV-1 strains in infected people.
Efficient chemical synthesis of human complement protein C3a
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3CC40537K
Abstract: We report the total chemical synthesis of human C3a by one-pot native chemical ligation of three unprotected peptide segments, followed by efficient in vitro folding that yielded the anaphylatoxin C3a in high yield and excellent purity. Synthetic C3a was fully active and its crystal structure at 2.1 Å resolution showed 3 helices and a C-terminal turn motif.
Protective effects of a potent C5a receptor antagonist on experimental acute limb ischemia-reperfusion in rats
Publisher: Elsevier BV
Date: 2004
DOI: 10.1016/J.JSS.2003.04.001
Abstract: The capacity of a potent C5a receptor antagonist to inhibit various parameters of local and remote organ injury following lower limb ischemia-reperfusion (I/R) in rats was investigated. Rats were subjected to 2 h bilateral hindlimb ischemia and 4 h reperfusion. Drug-treated rats received AcF-[OPdChaWR] (1 mg/kg) iv either 10 min before ischemia or 10 min prior to reperfusion, or orally (10 mg/kg) 30 min prior to ischemia. Levels of circulating creatine kinase (CK), lactate dehydrogenase (LDH), alanine and aspartate aminotransferase (ALT/AST), creatinine, blood urea nitrogen (BUN), polymorphonuclear leukocytes (PMNs), and calcium (Ca(++)) and potassium (K(+)) ions were determined. Other parameters measured included urinary protein levels, muscle edema, and myeloperoxidase (MPO) concentrations in the lung, liver, and muscle along with liver homogenate tumor necrosis factor-alpha (TNF-alpha) concentrations.L RESULTS: imb I/R injury was characterized by significant elevations of CK, LDH, ALT, AST, creatinine, BUN, proteinuria, PMNs, serum K(+), muscle edema, organ MPO, and liver homogenate TNF-alpha concentrations, but a significant reduction in serum Ca(2+) concentrations. When rats were treated with AcF-[OPdChaWR], there were significant improvements in all these parameters. These results indicate a pivotal role for C5a in inducing local and remote organ injury and suggest a possible new drug therapeutic category for preventing anticipated tissue injury associated with I/R.
Stereoelectronic Effects Dictate Molecular Conformation and Biological Function of Heterocyclic Amides
Publisher: American Chemical Society (ACS)
Date: 13-08-2014
DOI: 10.1021/JA506518T
Abstract: Heterocycles adjacent to amides can have important influences on molecular conformation due to stereoelectronic effects exerted by the heteroatom. This was shown for imidazole- and thiazole-amides by comparing low energy conformations (ab initio MP2 and DFT calculations), charge distribution, dipole moments, and known crystal structures which support a general principle. Switching a heteroatom from nitrogen to sulfur altered the amide conformation, producing different three-dimensional electrostatic surfaces. Differences were attributed to different dipole and orbital alignments and spectacularly translated into opposing agonist vs antagonist functions in modulating a G-protein coupled receptor for inflammatory protein complement C3a on human macrophages. Influences of the heteroatom were confirmed by locking the amide conformation using fused bicyclic rings. These findings show that stereoelectronic effects of heterocycles modulate molecular conformation and can impart strikingly different biological properties.
Antigen-loaded MR1 tetramers define T cell receptor heterogeneity in mucosal-associated invariant T cells
Publisher: Rockefeller University Press
Date: 07-10-2013
DOI: 10.1084/JEM.20130958
Abstract: Mucosal-associated invariant T cells (MAIT cells) express a semi-invariant T cell receptor (TCR) α-chain, TRAV1-2–TRAJ33, and are activated by vitamin B metabolites bound by the major histocompatibility complex (MHC)–related class I–like molecule, MR1. Understanding MAIT cell biology has been restrained by the lack of reagents to specifically identify and characterize these cells. Furthermore, the use of surrogate markers may misrepresent the MAIT cell population. We show that modified human MR1 tetramers loaded with the potent MAIT cell ligand, reduced 6-hydroxymethyl-8-d-ribityllumazine (rRL-6-CH2OH), specifically detect all human MAIT cells. Tetramer+ MAIT subsets were predominantly CD8+ or CD4−CD8−, although a small subset of CD4+ MAIT cells was also detected. Notably, most human CD8+ MAIT cells were CD8α+CD8β−/lo, implying predominant expression of CD8αα homodimers. Tetramer-sorted MAIT cells displayed a TH1 cytokine phenotype upon antigen-specific activation. Similarly, mouse MR1–rRL-6-CH2OH tetramers detected CD4+, CD4−CD8− and CD8+ MAIT cells in Vα19 transgenic mice. Both human and mouse MAIT cells expressed a broad TCR-β repertoire, and although the majority of human MAIT cells expressed TRAV1-2–TRAJ33, some expressed TRAJ12 or TRAJ20 genes in conjunction with TRAV1-2. Accordingly, MR1 tetramers allow precise phenotypic characterization of human and mouse MAIT cells and revealed unanticipated TCR heterogeneity in this population.
CD8 coreceptor engagement of MR1 enhances antigen responsiveness by human MAIT and other MR1-reactive T cells
Publisher: Rockefeller University Press
Date: 26-08-2022
DOI: 10.1084/JEM.20210828
Abstract: Mucosal-associated invariant T (MAIT) cells detect microbial infection via recognition of riboflavin-based antigens presented by the major histocompatibility complex class I (MHC-I)–related protein 1 (MR1). Most MAIT cells in human peripheral blood express CD8αα or CD8αβ coreceptors, and the binding site for CD8 on MHC-I molecules is relatively conserved in MR1. Yet, there is no direct evidence of CD8 interacting with MR1 or the functional consequences thereof. Similarly, the role of CD8αα in lymphocyte function remains ill-defined. Here, using newly developed MR1 tetramers, mutated at the CD8 binding site, and by determining the crystal structure of MR1–CD8αα, we show that CD8 engaged MR1, analogous to how it engages MHC-I molecules. CD8αα and CD8αβ enhanced MR1 binding and cytokine production by MAIT cells. Moreover, the CD8–MR1 interaction was critical for the recognition of folate-derived antigens by other MR1-reactive T cells. Together, our findings suggest that both CD8αα and CD8αβ act as functional coreceptors for MAIT and other MR1-reactive T cells.
Towards Arginine Mimetics
Publisher: Figshare
Date: 2019
A three-stage intrathymic development pathway for the mucosal-associated invariant T cell lineage
Publisher: Springer Science and Business Media LLC
Date: 26-09-2016
DOI: 10.1038/NI.3565
Abstract: Mucosal-associated invariant T cells (MAIT cells) detect microbial vitamin B2 derivatives presented by the antigen-presenting molecule MR1. Here we defined three developmental stages and checkpoints for the MAIT cell lineage in humans and mice. Stage 1 and stage 2 MAIT cells predominated in thymus, while stage 3 cells progressively increased in abundance extrathymically. Transition through each checkpoint was regulated by MR1, whereas the final checkpoint that generated mature functional MAIT cells was controlled by multiple factors, including the transcription factor PLZF and microbial colonization. Furthermore, stage 3 MAIT cell populations were expanded in mice deficient in the antigen-presenting molecule CD1d, suggestive of a niche shared by MAIT cells and natural killer T cells (NKT cells). Accordingly, this study maps the developmental pathway and checkpoints that control the generation of functional MAIT cells.
Computer Modelling and Synthesis of Deoxy and Monohydroxy Analogues of a Ribitylaminouracil Bacterial Metabolite that Potently Activates Human T Cells
Publisher: Wiley
Date: 07-11-2019
Abstract: 5-(2-Oxopropylideneamino)-6-d-ribitylaminouracil (5-OP-RU) is a natural product formed during bacterial synthesis of vitamin B2. It potently activates mucosal associated invariant T (MAIT) cells and has immunomodulatory, inflammatory, and anticancer properties. This highly polar and unstable compound forms a remarkably stable Schiff base with a lysine residue in major histocompatibility complex class I-related protein (MR1) expressed in antigen-presenting cells. Inspired by the importance of the ribityl moiety of 5-OP-RU for binding to both MR1 and the T cell receptor (TCR) on MAIT cells, each OH was removed in silico. DFT calculations and MD simulations revealed a very stable hydrogen bond between the C3'-OH and uracil N1H, which profoundly restricts flexibility and positioning of each ribityl-OH, potentially impacting their interactions with MR1 and TCR. By using deoxygenation strategies and kinetically controlled imine formation, four monodeoxyribityl and four monohydroxyalkyl analogues of 5-OP-RU were synthesised as new tools for probing T cell activation mechanisms.
Update 1 of: Over One Hundred Peptide-Activated G Protein-Coupled Receptors Recognize Ligands with Turn Structure
Publisher: American Chemical Society (ACS)
Date: 31-03-2010
DOI: 10.1021/CR900344W
Modular α-helical mimetics with antiviral activity against respiratory syncitial virus
Publisher: American Chemical Society (ACS)
Date: 14-09-2006
DOI: 10.1021/JA064058A
Abstract: A 13-residue peptide sequence from a respiratory syncitial virus fusion protein was constrained in an alpha-helical conformation by fusing two back-to-back cyclic alpha-turn mimetics. The resulting peptide, Ac-(3-->7 8-->12)-bicyclo-FP[KDEFD][KSIRD]V-NH(2), was highly alpha-helical in water by CD and NMR spectroscopy, correctly positioning crucial binding residues (F488, I491, V493) on one face of the helix and side chain-side chain linkers on a noninteracting face of the helix. This compound displayed potent activity in both a recombinant fusion assay and an RSV antiviral assay (IC(50) = 36 nM) and demonstrates for the first time that back-to-back modular alpha-helix mimetics can produce functional antagonists of important protein-protein interactions.
Correction: Downsizing the BAD BH3 peptide to small constrained α-helices with improved ligand efficiency
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6OB90178F
Abstract: Correction for ‘Downsizing the BAD BH3 peptide to small constrained α-helices with improved ligand efficiency’ by Nicholas E. Shepherd et al. , Org. Biomol. Chem. , 2016, DOI: 10.1039/c6ob02185a.
A specialized tyrosine-based endocytosis signal in MR1 controls antigen presentation to MAIT cells
Publisher: Rockefeller University Press
Date: 21-09-2022
Abstract: MR1 is a highly conserved microbial immune-detection system in mammals. It captures vitamin B–related metabolite antigens from erse microbes and presents them at the cell surface to stimulate MR1-restricted lymphocytes including mucosal-associated invariant T (MAIT) cells. MR1 presentation and MAIT cell recognition mediate homeostasis through host defense and tissue repair. The cellular mechanisms regulating MR1 cell surface expression are critical to its function and MAIT cell recognition, yet they are poorly defined. Here, we report that human MR1 is equipped with a tyrosine-based motif in its cytoplasmic domain that mediates low affinity binding with the endocytic adaptor protein 2 (AP2) complex. This interaction controls the kinetics of MR1 internalization from the cell surface and minimizes recycling. We propose MR1 uses AP2 endocytosis to define the duration of antigen presentation to MAIT cells and the detection of a microbial metabolic signature by the immune system.
Erratum: Latest developments in the treatment of inflammatory disease (Current Medicinal Chemistry (2005) vol. 12 (25) (2923-224))
Publisher: Bentham Science Publishers Ltd.
Date: 04-2007
Hepta and octapeptide agonists of protease-activated receptor 2
Publisher: Wiley
Date: 24-09-2007
DOI: 10.1002/PSC.912
Abstract: Protease-activated receptor 2 (PAR(2)) is a G protein-coupled cell surface receptor for trypsin-like enzymes. Proteolytic cleavage at a specific site in the extracellular N-terminus exposes a receptor-activating sequence, the 'tethered ligand', which binds intramolecularly to initiate receptor signalling. Peptide or small molecule agonists for PAR(2), devoid of the non-specific and proteolytic effects of enzyme activators, may be promising therapeutic agents for proliferative and inflammatory diseases reportedly mediated by PAR(2). Synthetic hexapeptides that correspond to the native tethered ligand of human or rodent PAR(2) (SLIGKV and SLIGRL, respectively) can activate the receptor independently of proteolytic cleavage however, known peptide agonists have much lower potency compared to protease-mediated activation. Here, we investigated the agonist activity of 94 hepta and octapeptide derivatives of the human and rodent PAR(2)-tethered ligand sequences in human airway epithelial (A549) cells which endogenously express PAR(2). Thirty synthetic peptides were found to be as potent as or more potent than SLIGRL on the basis of intracellular Ca(2+) responses. The more active peptide agonists were also examined for agonist cross-reactivity at PAR(1) in Chinese Hamster Ovary (CHO) cells that endogenously express functional PAR(1) but not PAR(2). Two potent and PAR(2)-selective agonists were further examined for their capacity to relax phenylephrine-contracted rat aortic rings. Our findings reveal an important role for carboxyl extensions to native PAR(2) activating peptides in potentiating agonist activity.
Taking the Myc out of cancer: toward therapeutic strategies to directly inhibit c-Myc
Publisher: Springer Science and Business Media LLC
Date: 04-01-2021
DOI: 10.1186/S12943-020-01291-6
Abstract: c-Myc is a transcription factor that is constitutively and aberrantly expressed in over 70% of human cancers. Its direct inhibition has been shown to trigger rapid tumor regression in mice with only mild and fully reversible side effects, suggesting this to be a viable therapeutic strategy. Here we reassess the challenges of directly targeting c-Myc, evaluate lessons learned from current inhibitors, and explore how future strategies such as miniaturisation of Omomyc and targeting E-box binding could facilitate translation of c-Myc inhibitors into the clinic.
Editorial
Publisher: Bentham Science Publishers Ltd.
Date: 12-2005
Non-peptide inhibitors of HIV-1 protease. Synthesis and structural evaluation of symmetric and non-symmetric naphthalenesulfonic acid analogues
Publisher: Elsevier BV
Date: 1996
Front Cover: Late‐Stage Hydrocarbon Conjugation and Cyclisation in Synthetic Peptides and Proteins (ChemBioChem 10/2021)
Publisher: Wiley
Date: 14-05-2021
Update 1 of: Proteases universally recognize beta strands in their active sites
Publisher: American Chemical Society (ACS)
Date: 09-06-2010
DOI: 10.1021/CR900368A
Biased Signaling by Agonists of Protease Activated Receptor 2
Publisher: American Chemical Society (ACS)
Date: 14-03-2017
DOI: 10.1021/ACSCHEMBIO.6B01088
Abstract: Protease activated receptor 2 (PAR2) is associated with metabolism, obesity, inflammatory, respiratory and gastrointestinal disorders, pain, cancer, and other diseases. The extracellular N-terminus of PAR2 is a common target for multiple proteases, which cleave it at different sites to generate different N-termini that activate different PAR2-mediated intracellular signaling pathways. There are no synthetic PAR2 ligands that reproduce the same signaling profiles and potencies as proteases. Structure-activity relationships here for 26 compounds spanned a signaling bias over 3 log units, culminating in three small ligands as biased agonist tools for interrogating PAR2 functions. DF253 (2f-LAAAAI-NH
High Cell Permeability Does Not Predict Oral Bioavailability for Analogues of Cyclic Heptapeptide Sanguinamide A
Publisher: CSIRO Publishing
Date: 2020
DOI: 10.1071/CH19479
Abstract: The cyclic heptapeptide derivative, sanguinamide A, is a model scaffold for studying how component amino acids, heterocycles, and N-methylation influence membrane permeability and oral bioavailability. Membrane permeable sanguinamide A analogues have been reported, but there is limited data on their pharmacokinetic properties invivo. Here we report pharmacokinetic properties for highly cell and membrane permeable sanguinamide A analogues in rats and find that there is no correlation between reported permeability invitro and oral bioavailability invivo. We show that N-methylation of sanguinamide A analogues gives compounds with greater flexibility, greater susceptibility to degradation by rat liver microsomes, and lower oral bioavailability in rats.
Effect of a protease‐activated receptor‐2 antagonist (GB88 ) on inflammation‐related loss of alveolar bone in periodontal disease
Publisher: Wiley
Date: 31-03-2023
DOI: 10.1111/JRE.13120
Abstract: Protease‐activated receptor‐2 (PAR 2 ), a pro‐inflammatory G‐protein coupled receptor, has been associated with pathogenesis of periodontitis and the resulting bone loss caused by oral pathogens, including the keystone pathogen Porphyromonas gingivalis ( P. gingivalis ). We hypothesised that administration of a PAR 2 antagonist, GB88, might prevent inflammation and subsequent alveolar bone resorption in a mouse model of periodontal disease. Periodontitis was induced in mice by oral inoculations with P. gingivalis for a total of eight times over 24 days. The infected mice were treated with either GB88 or vehicle for the duration of the trial. Following euthanasia on day 56, serum was collected and used for the detection of mast cell tryptase. The right maxillae were defleshed and stained with methylene blue to measure the exposed cementum in molar teeth. The left maxillae were prepared for cryosections followed by staining for tartrate‐resistant acid phosphatase to identify osteoclasts or with toluidine blue to identify mast cells. Reverse transcription quantitative PCR (RT‐qPCR) was used to quantify the expression of inflammatory cytokines in the gingival tissue. Supernatants of T‐lymphocyte cultures isolated from the regional lymph nodes were assayed using a cytometric bead array to measure the Th1/Th2/Th17 cytokine levels. Measurement of the exposed cementum showed that GB88 reduced P. gingivalis ‐induced alveolar bone loss by up to 69%. GB88 also prevented the increase in osteoclast numbers observed in the infected mice. Serum tryptase levels were significantly elevated in both the infected groups, and not altered by treatment. RT‐qPCR showed that GB88 prevented the upregulation of Il1b , Il6 , Ifng and Cd11b . In T‐lymphocyte supernatants, only IFNγ and IL‐17A levels were increased in response to infection, but this was prevented by GB88 treatment. GB88 significantly reduced osteoclastic alveolar bone loss in mice infected with P. gingivalis , seemingly by preventing the upregulation of several inflammatory cytokines. PAR 2 antagonism may be an effective treatment strategy for periodontal disease.
C5a Receptor (CD88) Inhibition Improves Hypothermia-Induced Neuroprotection in an In Vitro Ischemic Model
Publisher: Springer Science and Business Media LLC
Date: 17-01-2012
DOI: 10.1007/S12017-012-8167-0
Abstract: The concept of 'salvageble penumbra' has prompted both scientists and physicians to explore various neuroprotective approaches that could be beneficial during stroke therapy. Unfortunately, most of them have proved ineffective in targeting multiple cellular death cascades incited within the ischemic penumbra. Hypothermia has been shown to be capable of addressing this problem to some extent. Although many studies have shown that hypothermia targets several cellular processes, its effects on innate immune receptor-mediated apoptotic death still remain unclear. Moreover, whether inhibiting the signaling of innate immune receptors like complement anaphylatoxin C5a receptor (CD88) plays a role in this hypothermic neuroprotection still need to be deciphered. Using various types of ischemic insults in different neuronal cells, we confirm that hypothermia does indeed attenuate apoptotic neuronal cell death in vitro and this effect can be further enhanced by pharmacologically blocking or knocking out CD88. Thus, our study raises a promising therapeutic possibility of adding CD88 antagonists along with hypothermia to improve stroke outcomes.
Comparative α‐Helicity of Cyclic Pentapeptides in Water
Publisher: Wiley
Date: 14-05-2014
Abstract: Helix-constrained polypeptides have attracted great interest for modulating protein-protein interactions (PPI). It is not known which are the most effective helix-inducing strategies for designing PPI agonists/antagonists. Cyclization linkers (X1-X5) were compared here, using circular dichroism and 2D NMR spectroscopy, for α-helix induction in simple model pentapeptides, Ac-cyclo(1,5)-[X1-Ala-Ala-Ala-X5]-NH2, in water. In this very stringent test of helix induction, a Lys1→Asp5 lactam linker conferred greatest α-helicity, hydrocarbon and triazole linkers induced a mix of α- and 3₁₀-helicity, while thio- and dithioether linkers produced less helicity. The lactam-linked cyclic pentapeptide was also the most effective α-helix nucleator attached to a 13-residue model peptide.
The histone deacetylase Hdac7 supports LPS-inducible glycolysis and Il-1β production in murine macrophages via distinct mechanisms
Publisher: Oxford University Press (OUP)
Date: 23-11-2021
Abstract: TLRs reprogram macrophage metabolism, enhancing glycolysis and promoting flux through the tricarboxylic acid cycle to enable histone acetylation and inflammatory gene expression. The histone deacetylase (HDAC) family of lysine deacetylases regulates both TLR-inducible glycolysis and inflammatory responses. Here, we show that the TLR4 agonist LPS, as well as agonists of other TLRs, rapidly increase enzymatic activity of the class IIa HDAC family (HDAC4, 5, 7, 9) in both primary human and murine macrophages. This response was abrogated in murine macrophages deficient in histone deacetylase 7 (Hdac7), highlighting a selective role for this specific lysine deacetylase during immediate macrophage activation. With the exception of the TLR3 agonist polyI:C, TLR-inducible activation of Hdac7 enzymatic activity required the MyD88 adaptor protein. The rapid glycolysis response, as assessed by extracellular acidification rate, was attenuated in Hdac7-deficient mouse macrophages responding to submaximal LPS concentrations. Surprisingly however, reconstitution of these cells with either wild-type or an enzyme-dead mutant of Hdac7 enhanced LPS-inducible glycolysis, whereas only the former promoted production of the inflammatory mediators Il-1β and Ccl2. Thus, Hdac7 enzymatic activity is required for TLR-inducible production of specific inflammatory mediators, whereas it acts in an enzyme-independent fashion to reprogram metabolism in macrophages responding to submaximal LPS concentrations. Hdac7 is thus a bifurcation point for regulated metabolism and inflammatory responses in macrophages. Taken together with existing literature, our findings support a model in which submaximal and maximal activation of macrophages via TLR4 instruct glycolysis through distinct mechanisms, leading to ergent biological responses.
Identification and characterization of bi-thiazole-2,2'-diamines as kinase inhibitory scaffolds.
Publisher: Elsevier BV
Date: 06-2013
DOI: 10.1016/J.BBAPAP.2013.02.001
Abstract: Based on bioinformatics interrogation of the genome, >500 mammalian protein kinases can be clustered within seven different groups. Of these kinases, the mitogen-activated protein kinase (MAPK) family forms part of the CMGC group of serine/threonine kinases that includes extracellular signal regulated kinases (ERKs), cJun N-terminal kinases (JNKs), and p38 MAPKs. With the JNKs considered attractive targets in the treatment of pathologies including diabetes and stroke, efforts have been directed to the discovery of new JNK inhibitory molecules that can be further developed as new therapeutics. Capitalizing on our biochemical understanding of JNK, we performed in silico screens of commercially available chemical databases to identify JNK1-interacting compounds and tested their in vitro JNK inhibitory activity. With in vitro and cell culture studies, we showed that the compound, 4'-methyl-N(2)-3-pyridinyl-4,5'-bi-1,3-thiazole-2,2'-diamine (JNK Docking (JD) compound 123, but not the related compound (4'-methyl-N~2~-(6-methyl-2-pyridinyl)-4,5'-bi-1,3-thiazole-2,2'-diamine (JD124), inhibited JNK1 activity towards a range of substrates. Molecular docking, saturation transfer difference NMR experiments and enzyme kinetic analyses revealed both ATP- and substrate-competitive inhibition of JNK by JD123. In characterizing JD123 further, we noted its ATP-competitive inhibition of the related p38-γ MAPK, but not ERK1, ERK2, or p38-α, p38-β or p38-δ. Further screening of a broad panel of kinases using 10μM JD123, identified inhibition of kinases including protein kinase Bβ (PKBβ/Aktβ). Appropriately modified thiazole diamines, as typified by JD123, thus provide a new chemical scaffold for development of inhibitors for the JNK and p38-γ MAPKs as well as other kinases that are also potential therapeutic targets such as PKBβ/Aktβ.
Downsizing Proto-oncogene cFos to Short Helix-Constrained Peptides That Bind Jun
Publisher: American Chemical Society (ACS)
Date: 21-06-2017
DOI: 10.1021/ACSCHEMBIO.7B00303
Abstract: The oncogenic transcription factor activator protein-1 (AP-1) is a DNA-binding protein that assembles through dimerization of Fos and Jun protein subunits, their leucine-rich helical sequences entwining into a coiled-coil structure. This study reports on downsizing the proto-oncogene cFos protein (380 residues) to shorter peptides (37-25 residues) modified with helix-inducing constraints to enhance binding to Jun. A crystal structure is reported for a 37-residue Fos-derived peptide (FosW) bound to Jun. This guided iterative downsizing of FosW to shorter peptide sequences that were constrained into stable water-soluble α-helices by connecting amino acid side chains to form cyclic pentapeptide components. Structural integrity in the presence and absence of Jun was assessed by circular dichroism spectroscopy, while the thermodynamics of binding to cFos was measured by isothermal titration calorimetry. A 25-residue constrained peptide, one-third shorter yet 25% more helical than the structurally characterized 37-residue Fos-derived peptide, retained 80% of the binding free energy as a result of preorganization in a Jun-binding helix conformation, with the entropy gain (TΔS = +3.2 kcal/mol) compensating for the enthalpy loss. Attaching a cell-penetrating peptide (TAT
Aqueous Dissolution of Alzheimer's Disease Aβ Amyloid Deposits by Biometal Depletion
Publisher: Elsevier BV
Date: 08-1999
Correction: Twists or turns: stabilising alpha vs. beta turns in tetrapeptides
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0SC90138E
Abstract: Correction for ‘Twists or turns: stabilising alpha vs. beta turns in tetrapeptides’ by Huy N. Hoang et al. , Chem. Sci. , 2019, 10 , 10595–10600, DOI: 10.1039/C9SC04153B.
Structure-Activity Relationships of Wollamide Cyclic Hexapeptides with Activity against Drug-Resistant and Intracellular Mycobacterium tuberculosis.
Publisher: American Society for Microbiology
Date: 03-2019
DOI: 10.1128/AAC.01773-18
Abstract: Wollamides are cyclic hexapeptides, recently isolated from an Australian soil Streptomyces isolate, that exhibit promising in vitro antimycobacterial activity against Mycobacterium bovis Bacille Calmette Guérin without displaying cytotoxicity against a panel of mammalian cells. Here, we report the synthesis and antimycobacterial activity of 36 new synthetic wollamides, collated with all known synthetic and natural wollamides, to reveal structure characteristics responsible for in vitro growth-inhibitory activity against Mycobacterium tuberculosis (H37Rv, H37Ra, CDC1551, HN878, and HN353).
Flexibility versus Rigidity for Orally Bioavailable Cyclic Hexapeptides
Publisher: Wiley
Date: 07-10-2015
Abstract: Cyclic peptides and macrocycles have the potential to be membrane permeable and orally bioavailable, despite often not complying with the "rule of five" used in medicinal chemistry to guide the discovery of oral drugs. Here we compare solvent-dependent three-dimensional structures of three cyclic hexapeptides containing d-amino acids, prolines, and intramolecular hydrogen bonds. Conformational rigidity rather than flexibility resulted in higher membrane permeability, metabolic stability and oral bioavailability, consistent with less polar surface exposure to solvent and a reduced entropy penalty for transition between polar and nonpolar environments.
Cyclic Penta- and Hexaleucine Peptides without N-Methylation Are Orally Absorbed
Publisher: American Chemical Society (ACS)
Date: 07-08-2014
DOI: 10.1021/ML5002823
The Future of Peptide-based Drugs
Publisher: Wiley
Date: 17-12-2013
DOI: 10.1111/CBDD.12055
Abstract: The suite of currently used drugs can be ided into two categories - traditional 'small molecule' drugs with typical molecular weights of 5000 Da that are not orally bioavailable and need to be delivered via injection. Due to their small size, conventional small molecule drugs may suffer from reduced target selectivity that often ultimately manifests in human side-effects, whereas protein therapeutics tend to be exquisitely specific for their targets due to many more interactions with them, but this comes at a cost of low bioavailability, poor membrane permeability, and metabolic instability. The time has now come to reinvestigate new drug leads that fit between these two molecular weight extremes, with the goal of combining advantages of small molecules (cost, conformational restriction, membrane permeability, metabolic stability, oral bioavailability) with those of proteins (natural components, target specificity, high potency). This article uses selected ex les of peptides to highlight the importance of peptide drugs, some potential new opportunities for their exploitation, and some difficult challenges ahead in this field.
Context and trade-offs characterize real-world threat detection systems: A review and comprehensive framework to improve research practice and resolve the translational crisis
Publisher: Elsevier BV
Date: 08-2020
Helical cyclic pentapeptides constrain HIV-1 Rev peptide for enhanced RNA binding
Publisher: Elsevier BV
Date: 10-2014
A Comparative Study of Impedance versus Optical Label-Free Systems Relative to Labelled Assays in a Predominantly Gi Coupled GPCR (C5aR) Signalling
Publisher: MDPI AG
Date: 26-07-2012
DOI: 10.3390/BIOS2030273
Proteolysis of human hemoglobin by schistosome cathepsin D
Publisher: Elsevier BV
Date: 2001
DOI: 10.1016/S0166-6851(00)00351-0
Abstract: Schistosomes feed on human blood. They employ proteases to degrade hemoglobin from ingested erythrocytes, using the residues released for amino acid metabolism. However, the identity and the role of the participating protease(s) are unclear and controversial. Confocal microscopy localized schistosomal cathepsin D to the parasite gastrodermis, and revealed elevated protease expression in females. At sub-cellular level, cathepsin D was localized to superficial digestive vacuoles of the gut and to cisternae of the gastrodermal rough endoplasmic reticulum. Schistosome cathepsin D, expressed in insect cells, autoactivated at pH 3.6 to a approximately 40 kDa form that cleaved the substrates o-aminobenzoyl-Ile-Glu-Phe-nitroPhe-Arg-leu-NH(2) and hemoglobin. The NH(2)-terminal residues of mature cathepsin D of Schistosoma japonicum and Schistosoma mansoni were Asn1 and Gly1, respectively, revealing that the proregion peptide was comprised of 35 residues. The proteases cleaved hemoglobin at pH 2.5--4.6, releasing numerous fragments. S. Japonicum cathepsin D cleaved at 13 sites, S. mansoni cathepsin D at 15 sites. Early cleavage sites were alpha Phe33-Leu34 and beta Phe41-Phe42, while others included alpha Leu109-Ala-110 and beta Leu14-Trp15, demonstrating a preference for bulky hydrophobic residues at P1 and P1'. Most of the schistosomal cathepsin D cleavage sites were discrete from those of human cathepsin D. The gastrodermal location, elevated expression in females, acidic pH optima, similar substrate preferences in two species, and the discrete substrate preferences compared with human cathepsin D together provide compelling support for the hypothesis that schistosomal cathepsin D plays an integral role in hemoglobin proteolysis, and might be selectively targeted by drugs based on protease inhibition.
A novel bicyclic enzyme inhibitor as a consensus peptidomimetic for the receptor-bound conformations of 12 peptidic inhibitors of HIV-1 protease
Publisher: American Chemical Society (ACS)
Date: 1996
DOI: 10.1021/JA960433V
Inhibitors of class I histone deacetylases attenuate thioacetamide‐induced liver fibrosis in mice by suppressing hepatic type 2 inflammation
Publisher: Wiley
Date: 17-08-2019
DOI: 10.1111/BPH.14768
Improving on Nature: Making a Cyclic Heptapeptide Orally Bioavailable
Publisher: Wiley
Date: 12-09-2014
Abstract: The use of peptides in medicine is limited by low membrane permeability, metabolic instability, high clearance, and negligible oral bioavailability. The prediction of oral bioavailability of drugs relies on physicochemical properties that favor passive permeability and oxidative metabolic stability, but these may not be useful for peptides. Here we investigate effects of heterocyclic constraints, intramolecular hydrogen bonds, and side chains on the oral bioavailability of cyclic heptapeptides. NMR-derived structures, amide H-D exchange rates, and temperature-dependent chemical shifts showed that the combination of rigidification, stronger hydrogen bonds, and solvent shielding by branched side chains enhances the oral bioavailability of cyclic heptapeptides in rats without the need for N-methylation.
Solution structure of methionine-oxidized amyloid β-peptide (1-40). Does oxidation affect conformational switching?
Publisher: American Chemical Society (ACS)
Date: 22-08-1998
DOI: 10.1021/BI9810757
Total Synthesis, Structure, and Oral Absorption of a Thiazole Cyclic Peptide, Sanguinamide A
Publisher: American Chemical Society (ACS)
Date: 06-11-2012
DOI: 10.1021/OL3027347
Abstract: The first total synthesis and three-dimensional solution structure are reported for sanguinamide A, a thiazole-containing cyclic peptide from the sea slug H. sanguineus. Solution phase fragment synthesis, solid phase fragment assembly, and solution macrocyclization were combined to give (1) in 10% yield. Spectral properties were identical for the natural product, requiring revision of its structure from (2) to (1). Intramolecular transannular hydrogen bonds help to bury polar atoms, which enables oral absorption from the gut.
Anti-malarial effect of histone deacetylation inhibitors and mammalian tumour cytodifferentiating agents
Publisher: Elsevier BV
Date: 05-2000
DOI: 10.1016/S0020-7519(00)00043-6
Abstract: The histones of Plasmodium falciparum represent a potential new target for anti-malarial compounds. A naturally occurring compound, apicidin, has recently been shown to inhibit the in vitro growth of P. falciparum. Apicidin was shown to hyperacetylate histones, suggesting that its mode of action is through histone deacetylase inhibition. We have tested the ability of known histone deacetylase inhibitors, mammalian tumour suppressor compounds, and cytodifferentiating agents to inhibit the in vitro growth of a drug sensitive and resistant strain of P. falciparum. Seven of the tested compounds had microM IC50 values, and trichostatin A, a histone deacetylation inhibitor and cytodifferentiating agent, was active at low nM concentrations. One compound, suberic acid bisdimethylamide, which selectively arrests tumour cells as opposed to normal mammalian cells, had an in vivo cytostatic effect against the acute murine malaria Plasmodium berghei, and one round of treatment with the compound failed to select for resistant mutations. These results suggest a promising role for histone deacetylase inhibitors and cytodifferentiating agents as antimalarial drug candidates.
Cell phenotype as a target of drug therapy in chronic inflammatory diseases
Publisher: Elsevier BV
Date: 02-2000
Structural mimicry of two cytochrome b562 interhelical loops using macrocycles constrained by oxazoles and thiazoles
Publisher: American Chemical Society (ACS)
Date: 13-04-2005
DOI: 10.1021/JA0455300
Abstract: A major chemical challenge is the structural mimicry of discontinuous protein surfaces brought into close proximity through polypeptide folding. We report the design, synthesis, and solution structure of a highly functionalized saddle-shaped macrocyclic scaffold, constrained by oxazoles and thiazoles, supporting two short peptide loops projecting orthogonally from the same face of the scaffold. This structural mimetic of two interhelical loops of cytochrome b(562) illustrates a promising approach to structurally mimicking discontinuous loops of proteins.
Potent inhibitors of West Nile Virus NS2B/NS3 protease
Publisher: Figshare
Date: 2019
Cyclic alpha-conotoxin peptidomimetic chimeras as potent GLP-1R agonists
Publisher: Elsevier BV
Date: 10-2015
DOI: 10.1016/J.EJMECH.2015.08.046
Abstract: Type 2 diabetes mellitus (T2DM) results from compromised pancreatic β-cell function, reduced insulin production, and lowered insulin sensitivity in target organs resulting in hyperglycemia. The GLP-1 hormone has two biologically active forms, GLP-1-(7-37) and GLP-1-(7-36)amide, which are equipotent at the glucagon-like peptide-1 receptor (GLP-1R). These peptides are central both to normal glucose metabolism and dysregulation in T2DM. Several structurally modified GLP-1 analogues are now approved drugs, and a number of other analogues are in clinical trials. None of these compounds is orally bioavailable and all require parenteral delivery. Recently, a number of smaller peptidomimetics containing 11-12 natural and unnatural amino acids have been identified that have similar insulin regulating profiles as GLP-1. The α-conotoxins are a class of disulfide rich peptide venoms isolated from cone snails, and are known for their highly constrained structures and resistance to enzymatic degradation. In this study, we examined whether 11-residue peptidomimetics incorporated into α-conotoxin scaffolds, forming monocyclic or bicyclic compounds constrained by disulfide bonds and/or backbone cyclization, could activate the GLP-1 receptor (GLP-1R). Several compounds showed potent (nanomolar) agonist activity at GLP-1R, as evaluated via cAMP signaling. In addition, HPLC retention times and in silico calculations suggested that mono- and bicyclic compounds had more favorable n-octanol/water partition coefficients according to the virtual partition coefficient model (vLogP), while maintaining a smaller radius of gyration compared to corresponding uncyclized peptidomimetics. Our findings suggest that cyclic peptidomimetics provide a potential avenue for future design of potent, compact ligands targeting GLP-1R and possessing improved physicochemical properties.
Cyclooligomerization of a Helix-bearing template into macrocycles bearing multiple helices
Publisher: American Chemical Society (ACS)
Date: 12-07-2008
DOI: 10.1021/OL801040C
Abstract: Cyclooligomerization was investigated for separating and spatially arranging helical peptides as discontinuous surfaces. Tetrapeptide H-[Ile-Ser-Lys(Ox)]-OH, containing a turn-inducing oxazole constraint, was connected through its lysine side chain via a beta-alanine linker to the C-terminus of a two-turn helical nonapeptide Ac-(cyclo-4,8)-LRL [KARAD](Aib). The resulting helix-appended template was self-condensed and cyclized to a library of macrocycles ( n = 2-6) containing multiple (2-6) helices. An NMR structure shows retention of alpha helicity in the cyclotrimer ( n = 3).
Species dependence for binding of small molecule agonist and antagonists to the C5a receptor on polymorphonuclear leukocytes
Publisher: Springer Science and Business Media LLC
Date: 2001
Abstract: This study investigated the receptor binding affinities of a C5a agonist and cyclic antagonists for polymorphonuclear leukocytes (PMNs) isolated from human, sheep, pig, dog, rabbit, guinea pig, rat and mouse. The affinities of the two small molecule antagonists, F-[OPdChaWR] and AcF-[OPdChaWR], and the agonist, YSFKPMPLaR, revealed large differences in C5a receptor (C5aR) affinities between species. The antagonists bound to human, rat and dog PMNs with similar high affinities, but with lower affinities to PMNs from all other species. The C5a agonist also bound with varying affinities between species, but showed a different affinity profile to the antagonists. In contrast, recombinant human C5a had similar affinity for PMNs of all species investigated. The low correlation between the affinities of the antagonists and the agonist between species either suggests that different receptor residues are important for distinguishing between agonist/antagonist binding, or that the agonist and antagonist peptides bind to two distinct sites within the C5aR.
Toward Drugs for Protease-Activated Receptor 2 (PAR2)
Publisher: American Chemical Society (ACS)
Date: 30-07-2013
DOI: 10.1021/JM400638V
Abstract: PAR2 has a distinctive functional phenotype among an unusual group of GPCRs called protease activated receptors, which self-activate after cleavage of their N-termini by mainly serine proteases. PAR2 is the most highly expressed PAR on certain immune cells, and it is activated by multiple proteases (but not thrombin) in inflammation. PAR2 is expressed on many types of primary human cells and cancer cells. PAR2 knockout mice and PAR2 agonists and antagonists have implicated PAR2 as a promising target in inflammatory conditions respiratory, gastrointestinal, metabolic, cardiovascular, and neurological dysfunction and cancers. This article summarizes salient features of PAR2 structure, activation, and function opportunities for disease intervention via PAR2 pharmacological properties of published or patented PAR2 modulators (small molecule agonists and antagonists, pepducins, antibodies) and some personal perspectives on limitations of assessing their properties and on promising new directions for PAR2 modulation.
Priming programed Mucosal-Associated Invariant T cells protect against systemic or local bacterial infection
Publisher: Research Square Platform LLC
Date: 15-07-2020
DOI: 10.21203/RS.3.RS-39302/V1
Abstract: Mucosal-Associated Invariant T (MAIT) cells have potent antibacterial functions. Their protective capacity, in vivo, has been demonstrated in mouse models, particularly of respiratory infections. We now show that during systemic infection of mice with Francisella tularensis Live Vaccine Strain (LVS), MAIT cell expansion was evident in the liver, lungs, kidney, spleen and blood. MAIT cells manifested a polarised Th1-like (termed “MAIT-1”) phenotype and cytokine profile that conferred a critical role in controlling bacterial load. After resolution of the primary infection, the expanded MAIT cells developed to a stable memory-like MAIT-1 cell population, suggesting a basis for vaccination and protection against subsequent challenge. Indeed, a systemic vaccination with synthetic ligand (5-OP-RU) in combination with CpG adjuvant boosted MAIT-1 cells and resulted in enhanced protection against systemic and local infections with F. tularensis and Legionella longbeachae. Our study highlights the potential utility of targeting MAIT cells to combat multiple bacterial pathogens.
Receptor residence time trumps drug-likeness and oral bioavailability in determining efficacy of complement C5a antagonists
Publisher: Springer Science and Business Media LLC
Date: 20-04-2016
DOI: 10.1038/SREP24575
Abstract: Drug discovery and translation are normally based on optimizing efficacy by increasing receptor affinity, functional potency, drug-likeness (rule-of-five compliance) and oral bioavailability. Here we demonstrate that residence time of a compound on its receptor has an overriding influence on efficacy, exemplified for antagonists of inflammatory protein complement C5a that activates immune cells and promotes disease. Three equipotent antagonists (3D53, W54011, JJ47) of inflammatory responses to C5a (3nM) were compared for drug-likeness, receptor affinity and antagonist potency in human macrophages, and anti-inflammatory efficacy in rats. Only the least drug-like antagonist (3D53) maintained potency in cells against higher C5a concentrations and had a much longer duration of action ( t 1/2 ~ 20 h) than W54011 or JJ47 ( t 1/2 ~ 1–3 h) in inhibiting macrophage responses. The unusually long residence time of 3D53 on its receptor was mechanistically probed by molecular dynamics simulations, which revealed long-lasting interactions that trap the antagonist within the receptor. Despite negligible oral bioavailability, 3D53 was much more orally efficacious than W54011 or JJ47 in preventing repeated agonist insults to induce rat paw oedema over 24 h. Thus, residence time on a receptor can trump drug-likeness in determining efficacy, even oral efficacy, of pharmacological agents.
Tumor-Associated Antigenic Peptides as Vaccine Candidates
Publisher: Wiley
Date: 18-03-2009
Connecting Hydrophobic Surfaces in Cyclic Peptides Increases Membrane Permeability
Publisher: Wiley
Date: 04-03-2021
Potent complement C3a receptor agonists derived from oxazole amino acids: Structure–activity relationships
Publisher: Elsevier BV
Date: 12-2015
DOI: 10.1016/J.BMCL.2015.10.038
Abstract: Potent ligands for the human complement C3a receptor (C3aR) were developed from the almost inactive tripeptide Leu-Ala-Arg corresponding to the three C-terminal residues of the endogenous peptide agonist C3a. The analogous Leu-Ser-Arg was modified by condensing the serine side chain with the leucine carbonyl with elimination of water to form leucine-oxazole-arginine. Subsequent elaboration with a variety of N-terminal amide capping groups produced agonists as potent as human C3a itself in stimulating Ca(2+) release from human macrophages. Structure-activity relationships are discussed.
Protease activated receptor 2 controls myelin development, resiliency and repair
Publisher: Wiley
Date: 18-09-2017
DOI: 10.1002/GLIA.23215
Rational design and synthesis of an orally bioavailable peptide guided by NMR amide temperature coefficients
Publisher: Proceedings of the National Academy of Sciences
Date: 21-11-2014
Abstract: Peptides are valuable leads for drug development, offering advantages over other molecular classes. Specifically, they can bind potently and selectively to drug targets, including protein–protein interactions that are too challenging for small-molecule therapeutics. However, peptides are poor drugs because of their low in vivo stability and poor oral bioavailability. We propose a strategy for improving the oral bioavailability of peptides by identifying appropriate amides for chemical modification using temperature coefficients measured by NMR. The modified peptides have improved solvation properties, making them more membrane permeable. This approach for identifying sites for modification is a rapid method for guiding peptide drug design.
A Cyclic β-Strand Tripeptide with an α-Helix Like CD Spectrum
Publisher: American Chemical Society (ACS)
Date: 17-06-2009
DOI: 10.1021/OL901181B
Abstract: A protein alpha-helix is defined by 3.6 amino acids per turn. Cyclization of the tripeptide Alanine-Leucine-Glutamate through a side chain to the N-terminus lactam bond produces cyclo-(1,3)-[ALE]-NH(2) which displays a circular dichroism spectrum typical of an alpha-helix backbone. However, proton NMR spectra show a novel cyclic peptide featuring two non-hydrogen-bonded antiparallel beta-strands connected by an Ala-Leu cis-amide bond. This ex le highlights that the common practice of characterizing alpha-helices by CD spectra alone can be misleading.
Recognition of Vitamin B Precursors and Byproducts by Mucosal Associated Invariant T Cells
Publisher: Elsevier BV
Date: 12-2015
Downsizing a human inflammatory protein to a small molecule with equal potency and functionality
Publisher: Springer Science and Business Media LLC
Date: 21-11-2013
DOI: 10.1038/NCOMMS3802
Abstract: A significant challenge in chemistry is to rationally reproduce the functional potency of a protein in a small molecule, which is cheaper to manufacture, non-immunogenic, and also both stable and bioavailable. Synthetic peptides corresponding to small bioactive protein surfaces do not form stable structures in water and do not exhibit the functional potencies of proteins. Here we describe a novel approach to growing small molecules with protein-like potencies from a functionally important amino acid of a protein. A 77-residue human inflammatory protein (complement C3a) important in innate immunity is rationally transformed to equipotent small molecules, using peptide surrogates that incorporate a turn-inducing heterocycle with correctly positioned hydrogen-bond-accepting atoms. Small molecule agonists (molecular weight <500 Da) examined for receptor affinity and cellular responses have the same high potencies, functional profile and specificity of action as C3a protein, but greater plasma stability and bioavailability.
Development of cell‐penetrating peptide‐based drug leads to inhibit MDMX:p53 and MDM2:p53 interactions
Publisher: Wiley
Date: 11-2016
DOI: 10.1002/BIP.22893
Abstract: The transcription factor p53 has a tumor suppressor role in leading damaged cells to apoptosis. Its activity is regulated/inhibited in healthy cells by the proteins MDM2 and MDMX. Overexpression of MDM2 and/or MDMX in cancer cells inactivates p53, facilitating tumor development. A 12-mer dual inhibitor peptide (pDI) was previously reported to be able to target and inhibit MDMX:p53 and MDM2:p53 interactions with nanomolar potency in vitro. With the aim of improving its cellular inhibitory activity, we produced a series of constrained pDI analogs featuring lactam staples that stabilize the bioactive helical conformation and fused them with a cell-penetrating peptide to increase cytosol delivery. We compared pDI and its analogs on their inhibitory potency, toxicity, and ability to enter cancer cells. Overall, the results show that these analogs keep their nanomolar affinity for MDM2 and MDMX and are highly active against cancer cells. © 2016 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 853-863, 2016.
A Novel Long‐Range n to π* Interaction Secures the Smallest known α‐Helix in Water
Publisher: Wiley
Date: 08-11-2019
Abstract: The introduction of an amide bond linking side chains of the first and fifth amino acids forms a cyclic pentapeptide that optimally stabilizes the smallest known α‐helix in water. The origin of the stabilization is unclear. The observed dependence of α‐helicity on the solvent and cyclization linker led us to discover a novel long‐range n to π* interaction between a main‐chain amide oxygen and a uniquely positioned carbonyl group in the linker of cyclic pentapeptides. CD and NMR spectra, NMR and X‐ray structures, modelling, and MD simulations reveal that this first ex le of a synthetically incorporated long‐range n to π* CO⋅⋅⋅C γ =Ο interaction uniquely enforces an almost perfect and remarkably stable peptide α‐helix in water but not in DMSO. This unusual interaction with a covalent amide bond outside the helical backbone suggests new approaches to synthetically stabilize peptide structures in water.
Flavones are inhibitors of HIV-1 proteinase
Publisher: Elsevier BV
Date: 10-1992
DOI: 10.1016/0006-291X(92)91103-W
Abstract: Substituted gamma-chromones were found to weakly inhibit HIV-1 proteinase, an important enzyme in the replication and processing of the AIDS virus. Chromones bearing hydroxyl substituents and a phenolic group at the 2-position (flavones) were the most active compounds and structure-activity relationships for a limited series of flavone inhibitors are presented. Dixon plots are reported and a possible mechanism for flavone-induced inhibition is proposed. The results are also compared with those for some structurally related non-peptidic inhibitors of HIV-1 proteinase. Since some flavonoid compounds have already been shown to have antiviral activity against AIDS, the present observations of anti-HIV-1 proteinase activity may be particularly significant.
Site-directed mutagenesis and kinetic studies of the West Nile virus NS3 protease identify key enzyme-substrate interactions
Publisher: Elsevier BV
Date: 2005
Is oxidative damage by β-amyloid and prion peptides mediated by hydrogen atom transfer from glycine α-carbon to methionine sulfur within β-sheets?
Publisher: American Chemical Society (ACS)
Date: 22-09-2000
DOI: 10.1021/JA994436U
Targeting quorum sensing and competence stimulation for antimicrobial chemotherapy
Publisher: Bentham Science Publishers Ltd.
Date: 08-2012
DOI: 10.2174/138945012803530233
Abstract: Bacterial resistance to antibiotics is now a serious problem, with traditional classes of antibiotics having gradually become ineffective. New drugs are therefore needed to target and inhibit novel pathways that affect the growth of bacteria. An important feature in the survival of bacteria is that they coordinate their efforts together as a colony via secreted auto-inducing molecules. Competence stimulating peptides (CSPs) are among the quorum sensing pheromones involved in this coordination. These peptides activate a two-component system in gram-negative bacteria, binding to and activating a histidine kinase receptor called ComD, which phosphorylates a response regulator called ComE, leading to gene expression and induction of competence. Competent bacteria are able to take up exogenous DNA and incorporate it into their own genome. By this mechanism bacteria are able to acquire and share genes encoding antibiotic resistance. Despite having been studied for over 30 years, this pathway has only recently begun to be explored as a novel approach to modulating bacterial growth. Antagonists of ComD might block the signaling cascade that leads to competence, while overstimulation of ComD might also reduce bacterial growth. One possible approach to inhibiting ComD is to examine peptide sequences of CSPs that activate ComD and attempt to constrain them to bioactive conformations, likely to have higher affinity due to pre-organization for recognition by the receptor. Thus, small molecules that mimic an alpha helical epitope of CSPs, the putative ComD binding domain, have been shown here to inhibit growth of bacteria such as S. pneumoniae. Such alpha helix mimetics may be valuable clues to antibacterial chemotherapeutic agents that utilize a new mechanism to control bacterial growth.
Potent Small Agonists of Protease Activated Receptor 2
Publisher: American Chemical Society (ACS)
Date: 03-12-2015
A cyclic metallopeptide induces α helicity in short peptide fragments of thermolysin
Publisher: Wiley
Date: 27-01-2003
A divergent transcriptional landscape underpins the development and functional branching of MAIT cells
Publisher: American Association for the Advancement of Science (AAAS)
Date: 11-2019
DOI: 10.1126/SCIIMMUNOL.AAY6039
Abstract: Characterizing MAIT cell development led to the identification of key regulators that specify MAIT cell fate in the thymus.
Catalytically active Dengue virus NS3 protease forms aggregates that are separable by size exclusion chromatography
Publisher: Elsevier BV
Date: 07-2002
DOI: 10.1016/S1046-5928(02)00005-0
Abstract: An active form of the Dengue virus protease NS3 (CF40.Gly.NS3pro) was expressed in Escherichia coli. This construct consists of a critical 40 amino acid cofactor domain from NS2B fused to the N-terminal 184 amino acid protease domain of NS3 via a flexible, covalent linker (Gly(4)SerGly(4)). The recombinantly produced protein is soluble and has a hexa-histidine tag engineered at the N-terminus for ease of purification using metal affinity chromatography. However, the presence of lower molecular weight impurities after affinity chromatography indicated the need for additional purification steps. The consistent appearance of these impurities suggested that they may be the products of proteolysis and/or auto-proteolysis. The latter possibility was subsequently excluded by the observation of the same impurities in a purified, catalytically inactive form of the recombinant protease (CF40.Gly.NS3pro.SA). Further analysis indicated that these impurities may represent premature translation termination products. Regardless of their origin, they were shown to form various sized aggregates with full-length CF40.Gly.NS3pro that can be separated by size exclusion chromatography, yielding fractions of active protease of sufficient purity for crystallisation trials. The ultimate goal of these studies is to obtain a crystal structure of a catalytically active form of the Dengue virus NS3 protease for structure-based drug design.
Over One Hundred Peptide-Activated G Protein-Coupled Receptors Recognize Ligands with Turn Structure
Publisher: American Chemical Society (ACS)
Date: 22-02-2005
DOI: 10.1021/CR040689G
Crystal Structures of Protein-Bound Cyclic Peptides
Publisher: American Chemical Society (ACS)
Date: 02-05-2019
DOI: 10.1021/ACS.CHEMREV.8B00807
Abstract: Cyclization is an important post-translational modification of peptides and proteins that confers key advantages such as protection from proteolytic degradation, altered solubility, membrane permeability, bioavailability, and especially restricted conformational freedom in water that allows the peptide backbone to adopt the major secondary structure elements found in proteins. Non-ribosomal synthesis in bacteria, fungi, and plants or synthetic chemistry can introduce unnatural amino acids and non-peptidic constraints that modify peptide backbones and side chains to fine-tune cyclic peptide structure. Structures can be potentially altered further upon binding to a protein in biological environments. Here we analyze three-dimensional crystal structures for 211 bioactive cyclic peptides bound to 65 different proteins. The protein-bound cyclic peptides were examined for similarities and differences in bonding modes, for main-chain and side-chain structure, and for the importance of polarity, hydrogen bonds, hydrophobic effects, and water molecules in interactions with proteins. Many protein-bound cyclic peptides show backbone structures like those (strands, sheets, turns, helices, loops, or distorted variations) found at protein-protein binding interfaces. However, the notion of macrocycles simply as privileged scaffolds that primarily project side-chain substituents for complementary interactions with proteins is dispelled here. Unlike small-molecule drugs, the cyclic peptides do not rely mainly upon hydrophobic and van der Waals interactions for protein binding they also use their main chain and side chains to form polar contacts and hydrogen bonds with proteins. Compared to small-molecule ligands, cyclic peptides can bind across larger, polar, and water-exposed protein surface areas, making many more contacts that can increase affinity, selectivity, biological activity, and ligand-receptor residence time. Cyclic peptides have a greater capacity than small-molecule drugs to modulate protein-protein interfaces that involve large, shallow, dynamic, polar, and water-exposed protein surfaces.
Potent cationic inhibitors of west Nile virus NS2B/NS3 protease with serum stability, cell permeability and antiviral activity
Publisher: American Chemical Society (ACS)
Date: 26-08-2008
DOI: 10.1021/JM800503Y
Abstract: West Nile virus (WNV) has spread rapidly around the globe, efficiently crossing species from migrating birds into humans and other mammals. The viral protease NS2B-NS3 is important for WNV replication and recognizes dibasic substrate sequences common to other flaviviral proteases but different from most mammalian proteases. Potent inhibitors of WNV protease with antiviral activity have been elusive to date. We report the smallest and most potent inhibitors known for this enzyme, cationic tripeptides with nonpeptidic caps at the N-terminus and aldehyde at the C-terminus. One of these, compound 3 ( Ki = 9 nM) is stable in serum (>90% intact after 3 h, 37 degrees C), cell permeable, and shows antiviral activity (IC 50 1.6 microM) without cytotoxicity (IC 50 >400 microM), thereby validating the approach of inhibiting WNV protease to suppress WNV replication.
Lymphoid suppression by cis-platinum(II)amines. What are the active agents?
Publisher: Elsevier BV
Date: 03-1982
DOI: 10.1016/0006-2952(82)90323-9
Abstract: Cisplatin and its various hydrolysis products were tested in vitro for their effects on the incorporation of [3H]thymidine into lymphocytes isolated from thymuses, spleens and stimulated lymph nodes of rats. Neither cisplatin nor the mu-hydroxo-bridged oligomers formed after hydrolysis significantly inhibited thymidine incorporation at pH 7.4. However, freshly neutralised cis-diaquodiammineplatinum(II) was a potent inhibitor of thymidine incorporation by all three lymphocyte populations. In other experiments, rats were given either cisplatin or one of its hydrolysis products i.p. Cells isolated 17 hr later from the thymuses of all of these animals incorporated much less [3H]thymidine into DNA in vitro than thymocytes from saline-injected control animals. None of the platinum species significantly affected either [3H]uridine incorporation or the oxidation of [14C]octanoate to 14CO2 by the thymocytes. Evidence for anation of di- and tri-nuclear mu-hydroxo-bridged platinum(II)amines by chloride has been obtained from spectrophotometric analyses and 195Pt-NMR studies. Thiols also reacted with these platinum complexes at different rates (cis-[(NH3)2Pt(H2O)2]2+ much greater than derived oligomers greater than cisplatin). Various mechanisms for lymphoid suppression by cisplatin and its hydrolysis products are considered. It is proposed that cisplatin and its mu-hydroxo-bridged derivatives owe their lymphotoxic activity primarily to their in vivo transformation to platinum species containing aquo ligands.
The α-Proteobacteria Wolbachia pipientis Protein Disulfide Machinery Has a Regulatory Mechanism Absent in γ-Proteobacteria
Publisher: Public Library of Science (PLoS)
Date: 25-11-2013
Antagonism of the proinflammatory and pronociceptive actions of canonical and biased agonists of protease-activated receptor-2
Publisher: Wiley
Date: 03-08-2016
DOI: 10.1111/BPH.13554
Nonpeptide ligands that target peptide-activated GPCRs in inflammation
Publisher: Bentham Science Publishers Ltd.
Date: 12-2005
DOI: 10.2174/092986705774462888
Abstract: The focus of this review is on G protein-coupled receptors (GPCRs) for which nonpeptidic ligands are known and have been evaluated for the treatment of inflammatory conditions. GPCRs are the most prevalent class of cell surface proteins in pharmaceutical research today, and GPCR-targeting drugs account for one tenth of worldwide pharmaceutical sales. Of over 800 human GPCRs identified to date, several hundred are activated by peptides roteins and just over 30 of these have been identified so far as potential therapeutic targets for the treatment of inflammatory diseases. This review highlights those GPCRs and over 60 structurally erse nonpeptidic compounds that interact with them and display pro- or anti- inflammatory properties. Among these GPCR targets are the receptors for peptides like bradykinin, chemokines, complement anaphylatoxins, corticotropin releasing factor, endothelins, melanocortins, tachykinins, urocortins, as well as the protease activated receptors (PARs). Other peptide activated GPCRs implicated in inflammation, like those that bind angiotensin II, N-formyl peptides, galanin, neuropeptide Y, opioids and oxytocin, are only briefly discussed because there is either less direct association with inflammation or few/no nonpeptidic antiinflammatory ligands known. While it is still very early in the development of antiinflammatory drugs that target GPCRs, there is already a wealth of information supporting their important roles as cellular sentries in inflammatory diseases. New opportunities are emerging to evaluate antiinflammatory activities of potent and selective GPCR-binding ligands, including those being developed for other disease indications. In summary, GPCRs deserve a great deal more attention as potential therapeutic targets in inflammatory diseases.
Association of Monogenic and Polygenic Risk With the Prevalence of Open-Angle Glaucoma.
Publisher: American Medical Association (AMA)
Date: 09-2021
Downsizing the BAD BH3 peptide to small constrained α-helices with improved ligand efficiency
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6OB02185A
Abstract: Using macrocycles to meet the challenge of reducing proteins to smaller molecules that maintain affinity and inhibitory potency for Bcl-xL.
Irritancy and anti-inflammatory activity of bis(η5-cyclopentadienyl)titanium(IV) complexes in rats
Publisher: Elsevier BV
Date: 03-1987
DOI: 10.1016/0009-2797(87)90007-X
Abstract: Dichloro-bis(eta 5-cyclopentadienyl)titanium(IV) and some related complexes were compared with cis-dichlorodiammineplatinum(II) in rats for acute anti-inflammatory activity against carrageenan paw oedema, anti-arthritic activity against developing and established adjuvant-induced polyarthritis, immunosuppressant activity in a local graft-vs. host assay, irritant effects at sites of administration (paw, skin, peritoneum) and nephro- and gastro-toxicities. These titanium complexes, like cisplatin and its hydrolysis products, in vivo exhibited both anti-inflammatory and anti-arthritic activity as well as immunosuppressant effects. Nephro- and gastro-toxicity were much less severe than in rats given platinum complexes. In vitro they selectively inhibited [3H]thymidine incorporation by isolated thymocytes and prevented the germination of radish seeds. When given intraperitoneally, the anti-inflammatory activity may partly be due to a counter-irritant phenomenon since the titanium derivatives elicited an acute peritoneal effusion if they were injected towards the omentum. However, when injected subcutaneously or applied in dimethylformamide or dimethylsulfoxide to the skin, they manifested both anti-inflammatory and anti-arthritic activity without irritancy or much local skin damage. They might therefore have the potential of being useful drugs, especially if released slowly.
Landscaping macrocyclic peptides: stapling hDM2-binding peptides for helicity, protein affinity, proteolytic stability and cell uptake
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D1CB00231G
Abstract: Surveying macrocycles for mimicking a helical tumor suppressor protein, resisting breakdown by proteases, and entering cancer cells.
Selective Hexapeptide Agonists and Antagonists for Human Complement C3a Receptor
Publisher: American Chemical Society (ACS)
Date: 08-06-2010
DOI: 10.1021/JM1003705
Abstract: Human anaphylatoxin C3a, formed through cleavage of complement protein C3, is a potent effector of innate immunity via activation of its G protein coupled receptor, human C3aR. Previously reported short peptide ligands for this receptor either have low potency or lack receptor selectivity. Here we report the first small peptide agonists that are both potent and selective for human C3aR, derived from structure-activity relationships of peptides based on the C-terminus of C3a. Affinity for C3aR was examined by competitive binding with (125)I-labeled C3a to human PBMCs [corrected], agonist versus antagonist activity measured using fluorescence detection of intracellular calcium, and general selectivity monitored by C3a-induced receptor desensitization. An NMR structure for an agonist in DMSO showed a beta-turn motif that may be important for C3aR binding and activation. Derivatization produced a noncompetitive and insurmountable antagonist of C3aR. Small molecule C3a agonists and antagonists may be valuable probes of immunity and inflammatory diseases.
Antiproliferative and phenotype-transforming antitumor agents derived from cysteine.
Publisher: American Chemical Society (ACS)
Date: 29-04-2004
DOI: 10.1021/JM030222I
Abstract: Selective destruction of malignant tumor cells without damaging normal cells is an important goal for cancer chemotherapy in the 21st century. Differentiating agents that transform cancer cells to either a nonproliferating or normal phenotype could potentially be tissue-specific and avoid side effects of current drugs. However, most compounds that are presently known to differentiate cancer cells are histone deacetylase inhibitors that are of low potency or suffer from low bioavailability, rapid metabolism, reversible differentiation, and nonselectivity for cancer cells over normal cells. Here we describe 36 nonpeptidic compounds derived from a simple cysteine scaffold, fused at the C-terminus to benzylamine, at the N-terminus to a small library of carboxylic acids, and at the S-terminus to 4-butanoyl hydroxamate. Six compounds were cytotoxic at nanomolar concentrations against a particularly aggressive human melanoma cell line (MM96L), four compounds showed selectivities of > or =5:1 for human melanoma over normal human cells (NFF), and four of the most potent compounds were further tested and found to be cytotoxic for six other human cancer cell lines (melanomas SK-MEL-28, DO4 prostate DU145 breast MCF-7 ovarian JAM, CI80-13S). The most active compounds typically caused hyperacetylation of histones, induced p21 expression, and reverted phenotype of surviving tumor cells to a normal morphology. Only one compound was given orally at 5 mg/kg to healthy rats to look for bioavailability, and it showed reasonably high levels in plasma (C(max) 6 microg/mL, T(max) 15 min) for at least 4 h. Results are sufficiently promising to support further work on refining this and related classes of compounds to an orally active, more tumor-selective, antitumor drug.
Chemically Diverse Helix-Constrained Peptides Using Selenocysteine Crosslinking
Publisher: American Chemical Society (ACS)
Date: 20-02-2018
DOI: 10.1021/ACS.ORGLETT.8B00233
Abstract: The use of selenocysteines and various cross-linkers to induce helicity in a bioactive peptide is described. The higher reactivity of selenocysteine, relative to cysteine, facilitates rapid cross-linking within unprotected linear peptides under mild aqueous conditions. Alkylating agents of variable topology and electrophilicity were used to link pairs of selenocysteines within a p53 peptide. Facile selenoether formation enables erse tailoring of the helical peptide structure.
HDAC7 Inhibition by Phenacetyl and Phenylbenzoyl Hydroxamates
Publisher: American Chemical Society (ACS)
Date: 11-02-2021
Pharmacological inhibition of protease‐activated receptor‐2 reduces crescent formation in rat nephrotoxic serum nephritis
Publisher: Wiley
Date: 25-03-2019
Abstract: Glomerular crescent formation is a hallmark of rapidly progressive forms of glomerulonephritis. Thrombosis and macrophage infiltration are features of crescent formation in human and experimental kidney disease. Protease-activated receptor-2 (PAR-2) is a G-protein coupled receptor that links coagulation and inflammation. This study investigated whether pharmacological inhibition of PAR-2 can suppress glomerular crescent formation in rat nephrotoxic serum nephritis (NTN). Disease was induced in Wistar Kyoto rats by immunisation with sheep IgG followed by administration of sheep nephrotoxic serum. Rats (n = 8/group) received the PAR-2 antagonist (GB88, 10 mg/kg .o.), vehicle or no treatment starting 3 days before nephrotoxic serum injection and continuing until day 14. Vehicle and untreated rats developed thrombosis and macrophage infiltration in the glomerular tuft and Bowman's space in conjunction with prominent crescent formation. Activation of JNK signalling and proliferation in parietal epithelial cells was associated with crescent formation. GB88 treatment significantly reduced crescent formation with a substantial reduction in glomerular thrombosis, reduced macrophage infiltration in Bowman's space, and reduced activation of parietal epithelial cells. However, GB88 did not protect against the development of proteinuria, renal function impairment, inflammation or tubular cell damage in the NTN model. In conclusion, PAR-2 plays a specific role in glomerular crescent formation by promoting glomerular thrombosis, macrophage accumulation in Bowman's space and activation of parietal epithelial cells.
Structures of peptide agonists for human protease activated receptor 2
Publisher: Elsevier BV
Date: 2012
DOI: 10.1016/J.BMCL.2011.12.029
Abstract: Protease activated receptor 2 (PAR2) is an unusual G-protein coupled receptor in being self-activated, after pruning of the N-terminus by serine proteases like trypsin and tryptase. Short synthetic peptides corresponding to the newly exposed N-terminal hexapeptide sequence also activate PAR2 on immunoinflammatory, cancer and many normal cell types. (1)H nuclear magnetic resonance (NMR) and circular dichroism (CD) spectroscopy were used here to search for structural clues to activating mechanisms of the hexapeptide agonists SLIGRL (rat), SLIGKV (human) and the peptidomimetic analogue, 2-furoyl-LIGRLO. Either with a free or acetyl capped N-terminus, these agonist peptides display significant propensity in aprotic (DMSO) or lipidic (water-SDS) solvents for turn-like conformations, which are predicted to be receptor-binding conformations in the transmembrane or loops region of PAR2. These motifs may be valuable for the design of small molecule PAR2 agonists and antagonists as prospective new drugs for regulating inflammatory and proliferative diseases.
Short Hydrophobic Peptides with Cyclic Constraints Are Potent Glucagon-like Peptide-1 Receptor (GLP-1R) Agonists
Publisher: American Chemical Society (ACS)
Date: 16-04-2015
DOI: 10.1021/ACS.JMEDCHEM.5B00166
Abstract: Cyclic constraints are incorporated into an 11-residue analogue of the N-terminus of glucagon-like peptide-1 (GLP-1) to investigate effects of structure on agonist activity. Cyclization through linking side chains of residues 2 and 5 or 5 and 9 produced agonists at nM concentrations in a cAMP assay. 2D NMR and CD spectra revealed an N-terminal β-turn and a C-terminal helix that differentially influenced affinity and agonist potency. These structures can inform development of small molecule agonists of the GLP-1 receptor to treat type 2 diabetes.
MAIT Cells Upregulate α4β7 in Response to Acute Simian Immunodeficiency Virus/Simian HIV Infection but Are Resistant to Peripheral Depletion in Pigtail Macaques
Publisher: The American Association of Immunologists
Date: 04-2019
Abstract: Mucosal-associated invariant T (MAIT) cells are nonconventional T lymphocytes that recognize bacterial metabolites presented by MR1. Whereas gut bacterial translocation and the loss/dysfunction of peripheral MAIT cells in HIV infection is well described, MAIT cells in nonhuman primate models are poorly characterized. We generated a pigtail macaque (PTM)–specific MR1 tetramer and characterized MAIT cells in serial s les from naive and SIV– or simian HIV–infected PTM. Although PTM MAIT cells generally resemble the phenotype and transcriptional profile of human MAIT cells, they exhibited uniquely low expression of the gut-homing marker α4β7 and were not enriched at the gut mucosa. PTM MAIT cells responded to SIV/simian HIV infection by proliferating and upregulating α4β7, coinciding with increased MAIT cell frequency in the rectum. By 36 wk of infection, PTM MAIT cells were activated and exhibited a loss of Tbet expression but were not depleted as in HIV infection. Our data suggest the following: 1) MAIT cell activation and exhaustion is uncoupled from the hallmark depletion of MAIT cells during HIV infection and 2) the lack of PTM MAIT cell enrichment at the gut mucosa may prevent depletion during chronic infection, providing a model to assess potential immunotherapeutic approaches to modify MAIT cell trafficking during HIV infection.
Characterisation of TNF-α-related peptides by high-performance liquid chromatography-mass spectrometry and high-performance liquid chromatography-tandem mass spectrometry
Publisher: Elsevier BV
Date: 08-1993
DOI: 10.1016/S0021-9673(99)87020-4
Abstract: Ion-spray triple quadrupole mass spectrometry and high-performance liquid chromatography were used to investigate the products from the solid phase synthesis of (H)-Leu-Thr-Glu-Asn-(OH), a TNF-alpha active-site probe. The target sequence was assembled using tert.-butoxycarbonyl (Boc) chemistry in stepwise fashion from the C-terminal on an Boc-Asn-OCH2-Pam-copoly(styrene- inylbenzene) resin [Pam = 4-(carboxamidomethyl)benzyl ester]. The crude product was deprotected and cleaved from the resin by HF-p-cresol treatment for 1 h at 0 degrees C. HPLC analysis at 214 nm indicated two late-eluting major products and an early-eluting product. Preparative HPLC demonstrated that the early-eluting product contained ca. 80% of the expected recovered s le mass. Each component was then directly analysed by mass spectrometry and tandem mass spectrometry. The early eluting peak was confirmed as the desired LTEN sequence. Synthesis of the same sequence using 9-fluorenyl methoxycarbonyl (Fmoc) chemistry gave an identical product and confirmed the above analysis. The most significant by-product was derived from arylation of the glutamyl group by the quencher p-cresol. The likely origins of the by-products are discussed.
Hydroxyquinones are competitive non-peptide inhibitors of HIV-1 proteinase
Publisher: Elsevier BV
Date: 11-1995
DOI: 10.1016/0167-4838(95)00183-U
Abstract: Quinones with one, two and three aromatic rings are a new class of micromolar non-peptidic inhibitors of HIV-1 proteinase, an enzyme essential for replication of Human Immunodeficiency Virus and an important drug target for AIDS. Substituted anthraquinones bearing hydroxyl substituents on one of their three rings were the most potent of these inhibitors. Comparisons with other small non-peptidic inhibitors that are now emerging, together with enzyme kinetic data indicating that alizarin is a competitive inhibitor, suggest that anthraquinones bind in the active-site groove of HIV-1 proteinase.
A small molecule C5a receptor antagonist protects kidneys from ischemia/reperfusion injury in rats
Publisher: Elsevier BV
Date: 2003
DOI: 10.1046/J.1523-1755.2003.00737.X
Abstract: C5a has been implicated in numerous pathophysiological conditions, including ischemia/reperfusion (I/R) injury of the kidney. We examined whether a novel and specific C5a receptor antagonist, the cyclic compound AcF-[OPdChaWR] could moderate I/R-induced renal injury in rats. Female Wistar rats were subjected to renal ischemia (60 min) and reperfusion (5 h). Rats were treated with either 1 mg/kg IV in 5% ethanol/saline or 10 mg/kg PO in 25% ethanol/saline prior to ischemia. I/R injury was characterized by significant tissue hemorrhage with increased microvascular permeability, elevated renal tissue levels of tumor necrosis factor-alpha (TNF-alpha) and myeloperoxidase (MPO), increased serum levels of creatinine and aspartate aminotransferase (AST) and hematuria. Pre-ischemic treatment with the C5a receptor (C5aR) antagonist (1 mg/kg IV or 10 mg/kg PO) substantially inhibited or prevented I/R-induced hematuria, vascular leakage, tissue levels of TNF-alpha and MPO, and serum levels of AST and creatinine. Histological examination of kidneys from antagonist pretreated I/R animals showed a marked reduction in tissue damage compared to drug-free I/R rats. This antagonist, however, did not inhibit complement-mediated lysis of red blood cells, suggesting unimpaired formation of the membrane attack complex (MAC). The results demonstrate for the first time that a selective antagonist of both human and rat C5a receptors, given either intravenously or orally, significantly protects the kidney from I/R injury in the rat. We conclude that C5a is an important pathogenic agent in renal I/R injury, and that C5a receptor antagonists may be useful therapeutic agents for the pretreatment of anticipated renal reperfusion injury in humans.
Substrate-based cyclic peptidomimetics of Phe-Ile-Val that inhibit HIV-1 protease using a novel enzyme-binding mode
Publisher: American Chemical Society (ACS)
Date: 1996
DOI: 10.1021/JA953790Z
An overview on the identification of MAIT cell antigens
Publisher: Wiley
Date: 15-05-2018
DOI: 10.1111/IMCB.12057
Abstract: Mucosal associated invariant T (MAIT) cells are restricted by the monomorphic MHC class I-like molecule, MHC-related protein-1 (MR1). Until 2012, the origin of the MAIT cell antigens (Ags) was unknown, although it was established that MAIT cells could be activated by a broad range of bacteria and yeasts, possibly suggesting a conserved Ag. Using a combination of protein chemistry, mass spectrometry, cellular biology, structural biology and small molecule chemistry, we discovered MR1 ligands derived from folic acid (vitamin B9) and from an intermediate in the microbial biosynthesis of riboflavin (vitamin B2). While the folate derivative 6-formylpterin generally inhibited MAIT cell activation, two riboflavin pathway derivatives, 5-(2-oxopropylideneamino)-6-D-ribitylaminouracil and 5-(2-oxoethylideneamino)-6-D-ribitylaminouracil, were potent MAIT cell agonists. Other intermediates and derivatives of riboflavin synthesis displayed weak or no MAIT cell activation. Collectively, these studies revealed that in addition to peptide and lipid-based Ags, small molecule natural product metabolites are also ligands that can activate T cells expressing αβ T-cell receptors, and here we recount this discovery.
Noncovalent tripeptidyl benzyl- And cyclohexyl-amine inhibitors of the cysteine protease caspase-1
Publisher: American Chemical Society (ACS)
Date: 19-02-2010
DOI: 10.1021/JM901790W
Abstract: Potent and noncovalent inhibitors of caspase-1 were produced by incorporating a secondary amine (reduced amide) isostere in place of the conventional electrophile (e.g., aldehyde) that normally confers high potency to cysteine protease inhibitors. Benzyl- or cyclohexylamines produced potent, reversible, and competitive inhibitors that were selective for caspase-1 (e.g., K(i) = 47 nM) over caspases 3 and 8 with minimal cytotoxicity. Unlike most cysteine protease inhibitors, these compounds do not react covalently and indiscriminately with thiols.
Ex VivoActivity of Histone Deacetylase Inhibitors against Multidrug-Resistant Clinical Isolates ofPlasmodium falciparumandP. vivax
Publisher: American Society for Microbiology
Date: 03-2011
DOI: 10.1128/AAC.01220-10
Abstract: Histone acetylation plays an important role in regulating gene transcription and silencing in Plasmodium falciparum . Histone deacetylase (HDAC) inhibitors, particularly those of the hydroxamate class, have been shown to have potent in vitro activity against drug-resistant and -sensitive laboratory strains of P. falciparum , raising their potential as a new class of antimalarial compounds. In the current study, stage-specific ex vivo susceptibility profiles of representative hydroxamate-based HDAC inhibitors suberoylanilide hydroxamic acid (SAHA), 2-ASA-9, and 2-ASA-14 (2-ASA-9 and 2-ASA-14 are 2-aminosuberic acid-based HDAC inhibitors) were assessed in multidrug-resistant clinical isolates of P. falciparum ( n = 24) and P. vivax ( n = 25) from Papua, Indonesia, using a modified schizont maturation assay. Submicromolar concentrations of SAHA, 2-ASA-9, and 2-ASA-14 inhibited the growth of both P. falciparum (median 50% inhibitory concentrations [IC 50 s] of 310, 533, and 266 nM) and P. vivax (median IC 50 s of 170, 503, and 278 nM). Inverse correlation patterns between HDAC inhibitors and chloroquine for P. falciparum and mefloquine for P. vivax indicate species-specific susceptibility profiles for HDAC inhibitors. These HDAC inhibitors were also found to be potent ex vivo against P . vivax schizont maturation, comparable to that in P. falciparum , suggesting that HDAC inhibitors may be promising candidates for antimalarial therapy in geographical locations where both species are endemic. Further studies optimizing the selectivity and in vivo efficacy of HDAC inhibitors in Plasmodium spp. and defining drug interaction with common antimalarial compounds are warranted to investigate the role of HDAC inhibitors in antimalarial therapy.
In silico screening of small molecule libraries using the dengue virus envelope E protein has identified compounds with antiviral activity against multiple flaviviruses
Publisher: Elsevier BV
Date: 12-2009
DOI: 10.1016/J.ANTIVIRAL.2009.09.007
Abstract: The flaviviruses comprise a large group of related viruses, many of which pose a significant global human health threat, most notably the dengue viruses (DENV), West Nile virus (WNV) and yellow fever virus (YFV). Flaviviruses enter host cells via fusion of the viral and cellular membranes, a process mediated by the major viral envelope protein E as it undergoes a low pH induced conformational change in the endosomal compartment of the host cell. This essential entry stage in the flavivirus life cycle provides an attractive target for the development of antiviral agents. We performed an in silico docking screen of the Maybridge chemical database within a previously described ligand binding pocket in the dengue E protein structure that is thought to play a key role in the conformational transitions that lead to membrane fusion. The biological activity of selected compounds identified from this screen revealed low micromolar antiviral potency against dengue virus for two of the compounds. Our results also provide the first evidence that compounds selected to bind to this ligand binding site on the flavivirus E protein abrogate fusion activity. Interestingly, one of these compounds also has antiviral activity against both WNV (kunjin strain) and YFV.
A 195pt and 15n n.m.r. study of the anticancer drug, cis-diamminedichloro-platinum(ii), and its hydrolysis and oligomerization products
Publisher: CSIRO Publishing
Date: 1981
DOI: 10.1071/CH9810659
Abstract: 195Pt and 15N n.m.r, spectra for aqueous solutions of the anti-cancer drug cis-diamminedichloroplatinum(II) and its hydrolysis and oligomerization products are reported. In the blood substituteHanks medium, conversion of cis-[Pt(15NH3)2(H20)2](NO3)2 into cis[PtCl2(15NH3)2], cis-[PtCl(H20)(15NH3)2]+,[Pt(15NH3)2OH]33+ and [Pt(15NH3)2OH]22+ has been observed, the reaction taking several hours at 30�C. In 0.15 M sodium chloride, both [Pt(NH3)2OH]33+ and[Pt(NH3)2OH]22+ are converted overnight into cis-[PtCl(H2O)(NH3)2]+. The infrared bands at 546 and 522 cm-1 in [Pt(NH3)2OH]2SO4 and at 520 cm-1 in [Pt(NH3)2OH]2(SO4)3 have been reassigned to Pt-N modes.
HDAC7 is an immunometabolic switch triaging danger signals for engagement of antimicrobial versus inflammatory responses in macrophages
Publisher: Proceedings of the National Academy of Sciences
Date: 17-01-2023
Abstract: The immune system must be able to respond to a myriad of different threats, each requiring a distinct type of response. Here, we demonstrate that the cytoplasmic lysine deacetylase HDAC7 in macrophages is a metabolic switch that triages danger signals to enable the most appropriate immune response. Lipopolysaccharide (LPS) and soluble signals indicating distal or far-away danger trigger HDAC7-dependent glycolysis and proinflammatory IL-1β production. In contrast, HDAC7 initiates the pentose phosphate pathway (PPP) for NADPH and reactive oxygen species (ROS) production in response to the more proximal threat of nearby bacteria, as exemplified by studies on uropathogenic Escherichia coli (UPEC). HDAC7-mediated PPP engagement via 6-phosphogluconate dehydrogenase (6PGD) generates NADPH for antimicrobial ROS production, as well as D-ribulose-5-phosphate (RL5P) that both synergizes with ROS for UPEC killing and suppresses selective inflammatory responses. This dual functionality of the HDAC7-6PGD-RL5P axis prioritizes responses to proximal threats. Our findings thus reveal that the PPP metabolite RL5P has both antimicrobial and immunomodulatory activities and that engagement of enzymes in catabolic versus anabolic metabolic pathways triages responses to different types of danger for generation of inflammatory versus antimicrobial responses, respectively.
Chemical biology down under
Publisher: Bentham Science Publishers Ltd.
Date: 08-2012
Histone Deacetylase Inhibitors In Inflammatory Disease
Publisher: Bentham Science Publishers Ltd.
Date: 02-2009
DOI: 10.2174/156802609788085250
Abstract: Lysine acetylation is becoming increasingly appreciated as a key post-translational modification in the endogenous regulation of protein function. The so-called histone acetyl transferases (HATs) and histone deacetylases (HDACs), best known for their roles in controlling chromatin remodeling via histone acetylation/deacetylation, are now known to modify a large number of non-histone proteins to control erse cell processes. In relation to inflammation, acetylation modulates the activity or function of cytokine receptors, nuclear hormone receptors, intracellular signaling molecules and transcription factors. Small molecule inhibitors of HDACs have been found to trigger both pro- and anti-inflammatory effects in a range of inflammation-relevant cell types. Although their inflammatory profiles have only just begun to be elucidated, some HDAC inhibitors are already showing therapeutic promise in animal models of inflammatory diseases such as arthritis, inflammatory bowel diseases, septic shock, ischemia-reperfusion injury, airways inflammation and asthma, diabetes, age-related macular degeneration, cardiovascular diseases, multiple sclerosis and other CNS and neurodegenerative diseases. This article describes those HDAC inhibitors which have been most examined to date for their potentially beneficial effects on inflammatory cells or in animal models of inflammatory disease.
Endoplasmic reticulum chaperones stabilize ligand-receptive MR1 molecules for efficient presentation of metabolite antigens
Publisher: Proceedings of the National Academy of Sciences
Date: 21-09-2020
Abstract: A newly discovered system for immunological detection of erse bacterial and fungal pathogens involves the MHC-like host protein called MR1. This molecule scavenges metabolites from the biosynthesis of riboflavin by microbes. MR1 presents these compounds on the surface of antigen-presenting cells, where they interact with T cells known as mucosal-associated invariant T cells and stimulate immunity. Critical aspects of the cell biology of metabolite presentation by MR1 are unknown. Here we generated a fluorescent antigen analog and use it to show that MR1 captures its metabolites within the endoplasmic reticulum. We describe proteins that maintain MR1 ready for metabolite binding in the endoplasmic reticulum to promote efficient pathogen detection. MR1 thus monitors extracellular microbial metabolites from within the cell.
Downsizing human, bacterial, and viral proteins to short water-stable alpha helices that maintain biological potency
Publisher: Proceedings of the National Academy of Sciences
Date: 11-06-2010
Abstract: Recombinant proteins are important therapeutics due to potent, highly specific, and nontoxic actions in vivo. However, they are expensive medicines to manufacture, chemically unstable, and difficult to administer with low patient uptake and compliance. Small molecule drugs are cheaper and more bioavailable, but less target-specific in vivo and often have associated side effects. Here we combine some advantages of proteins and small molecules by taking short amino acid sequences that confer potency and selectivity to proteins, and fixing them as small constrained molecules that are chemically and structurally stable and easy to make. Proteins often use short α-helices of just 1–4 helical turns (4–15 amino acids) to interact with biological targets, but peptides this short usually have negligible α-helicity in water. Here we show that short peptides, corresponding to helical epitopes from viral, bacterial, or human proteins, can be strategically fixed in highly α-helical structures in water. These helix-constrained compounds have similar biological potencies as proteins that bear the same helical sequences. Ex les are ( i ) a picomolar inhibitor of Respiratory Syncytial Virus F protein mediated fusion with host cells, ( ii ) a nanomolar inhibitor of RNA binding to the transporter protein HIV-Rev, ( iii ) a submicromolar inhibitor of Streptococcus pneumoniae growth induced by quorum sensing pheromone Competence Stimulating Peptide, and ( iv ) a picomolar agonist of the GPCR pain receptor opioid receptor like receptor ORL-1. This approach can be generally applicable to downsizing helical regions of proteins with broad applications to biology and medicine.
Recognition of vitamin B metabolites by mucosal-associated invariant T cells
Publisher: Springer Science and Business Media LLC
Date: 11-07-2013
DOI: 10.1038/NCOMMS3142
Abstract: The mucosal-associated invariant T-cell antigen receptor (MAIT TCR) recognizes MR1 presenting vitamin B metabolites. Here we describe the structures of a human MAIT TCR in complex with human MR1 presenting a non-stimulatory ligand derived from folic acid and an agonist ligand derived from a riboflavin metabolite. For both vitamin B antigens, the MAIT TCR docks in a conserved manner above MR1, thus acting as an innate-like pattern recognition receptor. The invariant MAIT TCR α-chain usage is attributable to MR1-mediated interactions that prise open the MR1 cleft to allow contact with the vitamin B metabolite. Although the non-stimulatory antigen does not contact the MAIT TCR, the stimulatory antigen does. This results in a higher affinity of the MAIT TCR for a stimulatory antigen in comparison with a non-stimulatory antigen. We formally demonstrate a structural basis for MAIT TCR recognition of vitamin B metabolites, while illuminating how TCRs recognize microbial metabolic signatures.
Late‐Stage Hydrocarbon Conjugation and Cyclisation in Synthetic Peptides and Proteins
Publisher: Wiley
Date: 15-03-2021
Abstract: The conventional S-alkylation of cysteine relies upon using activated electrophiles. Here we demonstrate high-yielding and selective S-alkylation and S-lipidation of cysteines in unprotected synthetic peptides and proteins by using weak electrophiles and a Zn
Conformationally Constrained Macrocycles That Mimic Tripeptide β-Strands in Water and Aprotic Solvents
Publisher: American Chemical Society (ACS)
Date: 24-04-2002
DOI: 10.1021/JA0256461
Abstract: The beta-strand conformation is unknown for short peptides in aqueous solution, yet it is a fundamental building block in proteins and the crucial recognition motif for proteolytic enzymes that enable formation and turnover of all proteins. To create a generalized scaffold as a peptidomimetic that is pre-organized in a beta-strand, we in idually synthesized a series of 15-22-membered macrocyclic analogues of tripeptides and analyzed their structures. Each cycle is highly constrained by two trans amide bonds and a planar aromatic ring with a short nonpeptidic linker between them. A measure of this ring strain is the restricted rotation of the component tyrosinyl aromatic ring (DeltaG(rot) 76.7 kJ mol(-1) (16-membered ring), 46.1 kJ mol(-1) (17-membered ring)) evidenced by variable temperature proton NMR spectra (DMF-d(7), 200-400 K). Unusually large amide coupling constants ((3)J(NH-CHalpha) 9-10 Hz) corresponding to large dihedral angles were detected in both protic and aprotic solvents for these macrocycles, consistent with a high degree of structure in solution. The temperature dependence of all amide NH chemical shifts (Deltadelta/T 7-12 ppb/deg) precluded the presence of transannular hydrogen bonds that define alternative turn structures. Whereas similar sized conventional cyclic peptides usually exist in solution as an equilibrium mixture of multiple conformers, these macrocycles adopt a well-defined beta-strand structure even in water as revealed by 2-D NMR spectral data and by a structure calculation for the smallest (15-membered) and most constrained macrocycle. Macrocycles that are sufficiently constrained to exclusively adopt a beta-strand-mimicking structure in water may be useful pre-organized and generic templates for the design of compounds that interfere with beta-strand recognition in biology.
Fortified Coiled Coils: Enhancing Mechanical Stability with Lactam or Metal Staples
Publisher: Wiley
Date: 29-10-2020
Bicyclic Helical Peptides as Dual Inhibitors Selective for Bcl2A1 and Mcl-1 Proteins
Publisher: American Chemical Society (ACS)
Date: 27-03-2018
DOI: 10.1021/ACS.JMEDCHEM.8B00010
Abstract: A 26-residue peptide BimBH3 binds indiscriminately to multiple oncogenic Bcl2 proteins that regulate apoptosis of cancer cells. Specific inhibition of the BimBH3-Bcl2A1 protein-protein interaction was obtained in vitro and in cancer cells by shortening the peptide to 14 residues, inserting two cyclization constraints to stabilize a water-stable α-helix, and incorporating an N-terminal acrylamide electrophile for selective covalent bonding to Bcl2A1. Mass spectrometry of trypsin-digested bands on electrophoresis gels established covalent bonding of an electrophilic helix to just one of the three cysteines in Bcl2A1, the one (Cys55) at the BimBH3-Bcl2A1 protein-protein interaction interface. Optimizing the helix-inducing constraints and the sequence subsequently enabled electrophile removal without loss of inhibitor potency. The bicyclic helical peptides were potent, cell permeable, plasma-stable, dual inhibitors of Bcl2A1 and Mcl-1 with high selectivity over other Bcl2 proteins. One bicyclic peptide was shown to inhibit the interaction between a pro-apoptotic protein (Bim) and either endogenous Bcl2A1 or Mcl-1, to induce apoptosis of SKMel28 human melanoma cells, and to sensitize them for enhanced cell death by the anticancer drug etoposide. These approaches look promising for chemically silencing intracellular proteins.
A refined agonist pharmacophore for protease activated receptor 2
Publisher: Elsevier BV
Date: 10-2007
DOI: 10.1016/J.BMCL.2007.08.026
Abstract: Protease activated receptor 2 (PAR(2)) is a G protein-coupled receptor implicated in inflammation and cancer. Only a few peptide agonists are known with greater potency than the native agonist SLIGRL-NH(2). Here we report 52 peptide agonists of PAR(2), 26 with activity at sub-micromolar concentrations, and one being iodinated for radioligand experiments. Potency was highest when the N- or C-termini of SLIGRL-NH(2) were modified, pointing to a new ligand pharmacophore model that may aid development of drug-like PAR(2) modulators.
T-cell activation by transitory neo-antigens derived from distinct microbial pathways
Publisher: Springer Science and Business Media LLC
Date: 02-04-2014
DOI: 10.1038/NATURE13160
Abstract: T cells discriminate between foreign and host molecules by recognizing distinct microbial molecules, predominantly peptides and lipids. Riboflavin precursors found in many bacteria and yeast also selectively activate mucosal-associated invariant T (MAIT) cells, an abundant population of innate-like T cells in humans. However, the genesis of these small organic molecules and their mode of presentation to MAIT cells by the major histocompatibility complex (MHC)-related protein MR1 (ref. 8) are not well understood. Here we show that MAIT-cell activation requires key genes encoding enzymes that form 5-amino-6-d-ribitylaminouracil (5-A-RU), an early intermediate in bacterial riboflavin synthesis. Although 5-A-RU does not bind MR1 or activate MAIT cells directly, it does form potent MAIT-activating antigens via non-enzymatic reactions with small molecules, such as glyoxal and methylglyoxal, which are derived from other metabolic pathways. The MAIT antigens formed by the reactions between 5-A-RU and glyoxal/methylglyoxal were simple adducts, 5-(2-oxoethylideneamino)-6-D-ribitylaminouracil (5-OE-RU) and 5-(2-oxopropylideneamino)-6-D-ribitylaminouracil (5-OP-RU), respectively, which bound to MR1 as shown by crystal structures of MAIT TCR ternary complexes. Although 5-OP-RU and 5-OE-RU are unstable intermediates, they became trapped by MR1 as reversible covalent Schiff base complexes. Mass spectra supported the capture by MR1 of 5-OP-RU and 5-OE-RU from bacterial cultures that activate MAIT cells, but not from non-activating bacteria, indicating that these MAIT antigens are present in a range of microbes. Thus, MR1 is able to capture, stabilize and present chemically unstable pyrimidine intermediates, which otherwise convert to lumazines, as potent antigens to MAIT cells. These pyrimidine adducts are microbial signatures for MAIT-cell immunosurveillance.
Stabilizing short-lived Schiff base derivatives of 5-aminouracils that activate mucosal-associated invariant T cells
Publisher: Springer Science and Business Media LLC
Date: 08-03-2017
DOI: 10.1038/NCOMMS14599
Abstract: Mucosal-associated invariant T (MAIT) cells are activated by unstable antigens formed by reactions of 5-amino-6- D -ribitylaminouracil (a vitamin B2 biosynthetic intermediate) with glycolysis metabolites such as methylglyoxal. Here we show superior preparations of antigens in dimethylsulfoxide, avoiding their rapid decomposition in water ( t 1/2 1.5 h, 37 °C). Antigen solution structures, MAIT cell activation potencies (EC 50 3–500 pM), and chemical stabilities are described. Computer analyses of antigen structures reveal stereochemical and energetic influences on MAIT cell activation, enabling design of a water stable synthetic antigen (EC 50 2 nM). Like native antigens, this antigen preparation induces MR1 refolding and upregulates surface expression of human MR1, forms MR1 tetramers that detect MAIT cells in human PBMCs, and stimulates cytokine expression (IFNγ, TNF) by human MAIT cells. These antigens also induce MAIT cell accumulation in mouse lungs after administration with a co-stimulant. These chemical and immunological findings provide new insights into antigen properties and MAIT cell activation.
Stereoelectronic Effects on Dienophile Separation Influence the Diels–Alder Synthesis of Molecular Clefts
Publisher: Wiley
Date: 04-12-2017
A Novel Long‐Range n to π* Interaction Secures the Smallest known α‐Helix in Water
Publisher: Wiley
Date: 08-11-2019
Abstract: The introduction of an amide bond linking side chains of the first and fifth amino acids forms a cyclic pentapeptide that optimally stabilizes the smallest known α‐helix in water. The origin of the stabilization is unclear. The observed dependence of α‐helicity on the solvent and cyclization linker led us to discover a novel long‐range n to π* interaction between a main‐chain amide oxygen and a uniquely positioned carbonyl group in the linker of cyclic pentapeptides. CD and NMR spectra, NMR and X‐ray structures, modelling, and MD simulations reveal that this first ex le of a synthetically incorporated long‐range n to π* CO⋅⋅⋅C γ =Ο interaction uniquely enforces an almost perfect and remarkably stable peptide α‐helix in water but not in DMSO. This unusual interaction with a covalent amide bond outside the helical backbone suggests new approaches to synthetically stabilize peptide structures in water.
Human mucosal-associated invariant T cells contribute to antiviral influenza immunity via IL-18–dependent activation
Publisher: Proceedings of the National Academy of Sciences
Date: 19-08-2016
Abstract: Mucosal-associated invariant T (MAIT) cells are innate-like T lymphocytes with potent antibacterial reactivity. In this study, we investigated whether MAIT cells also contribute to immunity against influenza A viruses. Compared with those who succumbed, hospitalized patients who recovered from severe avian H7N9 influenza infection had higher numbers of MAIT cells. Subsequent in vitro analysis established that MAIT cells from healthy donors are indirectly activated by influenza infection via an IL-18–dependent (but not IL-12–dependent) mechanism requiring the involvement of CD14 + monocytes. Our findings highlight the potential for MAIT cells to promote protective immunity in human influenza.
Potent Thiophene Antagonists of Human Complement C3a Receptor with Anti-Inflammatory Activity
Publisher: American Chemical Society (ACS)
Date: 07-01-2020
DOI: 10.1021/ACS.JMEDCHEM.9B00927
Abstract: Structure-activity relationships for a series of small-molecule thiophenes resulted in potent and selective antagonism of human Complement C3a receptor. The compounds are about 100-fold more potent than the most reported antagonist SB290157. A new compound JR14a was among the most potent of the new antagonists in vitro, assessed by (a) inhibition of intracellular calcium release (IC
Stapling peptides using cysteine crosslinking
Publisher: Wiley
Date: 11-2016
DOI: 10.1002/BIP.22877
Abstract: Stapled peptides are an emerging class of cyclic peptide molecules with enhanced biophysical properties such as conformational and proteolytic stability, cellular uptake and elevated binding affinity and specificity for their biological targets. Among the limited number of chemistries available for their synthesis, the cysteine-based stapling strategy has received considerable development in the last few years driven by facile access from cysteine-functionalized peptide precursors. Here we present some recent advances in peptide and protein stapling where the side-chains of cysteine residues are covalently connected with a range of different crosslinkers affording bisthioether macrocyclic peptides of varying topology and biophysical properties. © 2016 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 843-852, 2016.
Enzymatic characterization and homology model of a catalytically active recombinant West Nile Virus NS3 protease
Publisher: Elsevier BV
Date: 11-2004
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Amount: $577,120.00
Funder: Australian Research Council
View Funded ActivityLinkage Infrastructure, Equipment And Facilities - Grant ID: LE0238397
Start Date: 2001
End Date: 12-2002
Amount: $550,000.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP0210330
Start Date: 2002
End Date: 12-2004
Amount: $300,000.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP0210598
Start Date: 2002
End Date: 12-2006
Amount: $1,550,000.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP0770936
Start Date: 2007
End Date: 12-2009
Amount: $300,000.00
Funder: Australian Research Council
View Funded ActivitySpecial Research Initiatives - Grant ID: SR0354474
Start Date: 01-2004
End Date: 12-2004
Amount: $30,000.00
Funder: Australian Research Council
View Funded ActivitySpecial Research Initiatives - Grant ID: SR0354636
Start Date: 2004
End Date: 12-2004
Amount: $30,000.00
Funder: Australian Research Council
View Funded ActivityLinkage Infrastructure, Equipment And Facilities - Grant ID: LE100100226
Start Date: 07-2010
End Date: 08-2011
Amount: $424,000.00
Funder: Australian Research Council
View Funded ActivityLinkage Infrastructure, Equipment And Facilities - Grant ID: LE210100148
Start Date: 07-2021
End Date: 06-2023
Amount: $1,350,000.00
Funder: Australian Research Council
View Funded ActivityARC Centres Of Excellence - Grant ID: CE200100012
Start Date: 01-2021
End Date: 01-2028
Amount: $35,000,000.00
Funder: Australian Research Council
View Funded ActivitySpecial Research Initiatives - Grant ID: SR0354892
Start Date: 2004
End Date: 12-2004
Amount: $40,000.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP0559821
Start Date: 2005
End Date: 12-2008
Amount: $280,000.00
Funder: Australian Research Council
View Funded ActivityLinkage Infrastructure, Equipment And Facilities - Grant ID: LE120100015
Start Date: 03-2012
End Date: 02-2013
Amount: $630,000.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP1093245
Start Date: 2010
End Date: 12-2012
Amount: $900,000.00
Funder: Australian Research Council
View Funded ActivityLinkage Infrastructure, Equipment And Facilities - Grant ID: LE160100218
Start Date: 2016
End Date: 12-2016
Amount: $840,000.00
Funder: Australian Research Council
View Funded Activity