ORCID Profile
0000-0002-8820-3931
Current Organisations
University of Manchester
,
RWTH Aachen University
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D3GC00442B
Abstract: By using a very low catalyst loading, a wide range of cyclic sulfoximine derivatives, that represent common cores of bioactive products, can be prepared in good to excellent yields at room temperature in a short period of time.
Publisher: Springer Science and Business Media LLC
Date: 05-01-2015
Publisher: Oxford University Press (OUP)
Date: 18-04-2023
DOI: 10.1093/NAR/GKAD272
Abstract: In response to oxidative stress cells reprogram gene expression to enhance levels of antioxidant enzymes and promote survival. In Saccharomyces cerevisiae the polysome-interacting La-related proteins (LARPs) Slf1 and Sro9 aid adaptation of protein synthesis during stress by undetermined means. To gain insight in their mechanisms of action in stress responses, we determined LARP mRNA binding positions in stressed and unstressed cells. Both proteins bind within coding regions of stress-regulated antioxidant enzyme and other highly translated mRNAs in both optimal and stressed conditions. LARP interaction sites are framed and enriched with ribosome footprints suggesting ribosome–LARP–mRNA complexes are identified. Although stress-induced translation of antioxidant enzyme mRNAs is attenuated in slf1Δ, these mRNAs remain on polysomes. Focusing further on Slf1, we find it binds to both monosomes and disomes following RNase treatment. slf1Δ reduces disome enrichment during stress and alters programmed ribosome frameshifting rates. We propose that Slf1 is a ribosome-associated translational modulator that stabilises stalled/collided ribosomes, prevents ribosome frameshifting and so promotes translation of a set of highly-translated mRNAs that together facilitate cell survival and adaptation to stress.
Publisher: Wiley
Date: 12-06-2023
Abstract: Sulfondiimines are marginalized entities among nitrogen‐containing organosulfur compounds, despite offering promising properties for applications in various fields including medicinal and agrochemical. Herein, we present a metal‐free and rapid synthetic procedure for the synthesis of N ‐monosubstituted sulfondiimines that overcomes current limitations in their synthetic accessibility. Particularly, S , S ‐dialkyl substrates, which are commonly difficult to convert by existing methods, react well with a combination of iodine, 1,8‐diazabicyclo[5.4.0]undec‐7‐en (DBU), and iminoiodinanes (PhINR) in acetonitrile (MeCN) to furnish the corresponding sulfondiimines in yields up to 85 % (25 ex les). Valuable “free” N H‐ N ′H‐sulfondiimines can then be accessed by N ‐deprotection under mild reaction conditions. Several experimental observations suggest a mechanistic pathway erging from the common radical‐based iodine/iminoiodinane mechanism. Based on the experimental results in combination with data obtained by 1 H NMR spectroscopy, ESI mass spectrometry, and crystallographic analysis we propose a direct amination from PhINNs and a reaction path via a cationic iodonitrene.
Publisher: Springer Science and Business Media LLC
Date: 27-10-2017
Publisher: Wiley
Date: 12-06-2023
Abstract: Sulfondiimines are marginalized entities among nitrogen‐containing organosulfur compounds, despite offering promising properties for applications in various fields including medicinal and agrochemical. Herein, we present a metal‐free and rapid synthetic procedure for the synthesis of N ‐monosubstituted sulfondiimines that overcomes current limitations in their synthetic accessibility. Particularly, S , S ‐dialkyl substrates, which are commonly difficult to convert by existing methods, react well with a combination of iodine, 1,8‐diazabicyclo[5.4.0]undec‐7‐en (DBU), and iminoiodinanes (PhINR) in acetonitrile (MeCN) to furnish the corresponding sulfondiimines in yields up to 85 % (25 ex les). Valuable “free” N H‐ N ′H‐sulfondiimines can then be accessed by N ‐deprotection under mild reaction conditions. Several experimental observations suggest a mechanistic pathway erging from the common radical‐based iodine/iminoiodinane mechanism. Based on the experimental results in combination with data obtained by 1 H NMR spectroscopy, ESI mass spectrometry, and crystallographic analysis we propose a direct amination from PhINNs and a reaction path via a cationic iodonitrene.
Publisher: Public Library of Science (PLoS)
Date: 08-01-2015
Publisher: Wiley
Date: 30-01-2007
Abstract: The initial steps of an enantioselective Diels-Alder reaction catalyzed by a CuII-bissulfoximine complex were followed by EXAFS (EXAFS=extended X-ray absorption fine structure), EPR (EPR=electron paramagnetic resonance) spectroscopy (CW-EPR, FID-detected EPR, pulse ENDOR, HYSCORE CW=continuous wave ENDOR=electron nuclear double resonance HYSCORE=hyperfine sublevel correlation FID=free induction decay), and UV-visible spectroscopy. The complexes formed between the parent CuX2 (X=Cl-, Br-, TfO-, SbF6-) salts, the chiral bissulfoximine ligand (S,S)-1, and N-(1-oxoprop-2-en-1-yl)oxazolidin-2-one (2) as the substrate in CH2Cl2 were investigated in frozen and fluid solution. In all cases, penta- or hexacoordinated CuII centers were established. The complexes with counterions indicating high stereoselectivity (TfO- and SbF6-) reveal one unique species in which substrate 2 binds to pseudoequatorial positions (via O atoms), shifting the counterions to axial locations. On the other hand, those lacking stereoselectivity (X=Cl- and Br-) form two species in which the parent halogen anions remain at equatorial positions preventing the formation of geometries compatible with those found for X=TfO- and SbF6-.
Publisher: Public Library of Science (PLoS)
Date: 14-05-2015
Publisher: Springer Science and Business Media LLC
Date: 23-10-2015
DOI: 10.1038/SREP15518
Abstract: The PUF family of RNA-binding proteins regulate gene expression post-transcriptionally. Saccharomyces cerevisiae Puf3p is characterised as binding nuclear-encoded mRNAs specifying mitochondrial proteins. Extensive studies of its regulation of COX17 demonstrate its role in mRNA decay. Using integrated genome-wide approaches we define an expanded set of Puf3p target mRNAs and quantitatively assessed the global impact of loss of PUF3 on gene expression using mRNA and polysome profiling and quantitative proteomics. In agreement with prior studies, our sequencing of affinity-purified Puf3-TAP associated mRNAs (RIP-seq) identified mRNAs encoding mitochondrially-targeted proteins. Additionally, we also found 720 new mRNA targets that predominantly encode proteins that enter the nucleus. Comparing transcript levels in wild-type and puf3 ∆ cells revealed that only a small fraction of mRNA levels alter, suggesting Puf3p determines mRNA stability for only a limited subset of its target mRNAs. Finally, proteomic and translatomic studies suggest that loss of Puf3p has widespread, but modest, impact on mRNA translation. Taken together our integrated multi-omics data point to multiple classes of Puf3p targets, which display coherent post-transcriptional regulatory properties and suggest Puf3p plays a broad, but nuanced, role in the fine-tuning of gene expression.
Publisher: Springer Science and Business Media LLC
Date: 21-05-2018
DOI: 10.1038/S41598-018-26170-5
Abstract: The transcriptional responses of yeast cells to erse stresses typically include gene activation and repression. Specific stress defense, citric acid cycle and oxidative phosphorylation genes are activated, whereas protein synthesis genes are coordinately repressed. This view was achieved from comparative transcriptomic experiments delineating sets of genes whose expression greatly changed with specific stresses. Less attention has been paid to the biological significance of 1) consistent, albeit modest, changes in RNA levels across multiple conditions, and 2) the global gene expression correlations observed when comparing numerous genome-wide studies. To address this, we performed a meta-analysis of 1379 microarray-based experiments in yeast, and identified 1388 blocks of RNAs whose expression changes correlate across multiple and erse conditions. Many of these blocks represent sets of functionally-related RNAs that act in a coordinated fashion under normal and stress conditions, and map to global cell defense and growth responses. Subsequently, we used the blocks to analyze novel RNA-seq experiments, demonstrating their utility and confirming the conclusions drawn from the meta-analysis. Our results provide a new framework for understanding the biological significance of changes in gene expression: ‘archetypal’ transcriptional blocks that are regulated in a concerted fashion in response to external stimuli.
Publisher: Wiley
Date: 09-02-2023
Abstract: Copper‐catalyzed cross‐coupling reactions of α‐bromoaryl N H‐sulfoximines with elemental sulfur lead to benzo[ d ][1,3,2]dithiazole‐1‐oxides, which represent a new class of three‐dimensional heterocycles. The reactions proceed under mild conditions showing good functional group and heterocycle tolerance. By imination/oxidation, the initial cross‐coupling products can be converted to unprecedented cyclic sulfonimidamides derivatives. Furthermore, a seven‐membered heterocycle was obtained by a ruthenium‐catalyzed ring‐expansion with ethyl propiolate. magnified image
Publisher: Springer Science and Business Media LLC
Date: 22-11-2018
DOI: 10.1038/S41467-018-07260-4
Abstract: Genome-wide association studies (GWAS) have identified loci of chronic kidney disease-defining traits (CKD-dt). Molecular mechanisms underlying these associations remain elusive. Using 280 kidney transcriptomes and 9958 gene expression profiles from 44 non-renal tissues we uncover gene expression partners (eGenes) for 88.9% of CKD-dt GWAS loci. Through epigenomic chromatin segmentation analysis and variant effect prediction we annotate functional consequences to 74% of these loci. Our colocalisation analysis and Mendelian randomisation in ,000 subjects demonstrate causal effects of three eGenes ( NAT8B , CASP9 and MUC1 ) on estimated glomerular filtration rate. We identify a common alternative splice variant in MUC1 (a gene responsible for rare Mendelian form of kidney disease) and observe increased renal expression of a specific MUC1 mRNA isoform as a plausible molecular mechanism of the GWAS association signal. These data highlight the variants and genes underpinning the associations uncovered in GWAS of CKD-dt.
Publisher: Wiley
Date: 11-2006
DOI: 10.1110/PS.062406706
Publisher: American Chemical Society (ACS)
Date: 29-04-2003
DOI: 10.1021/JA027870W
Abstract: The structure of Cu(II) complex 3 formed within the course of a stereoselective Diels-Alder reaction was investigated by EXAFS, CW-EPR at X- and W-band, HYSCORE, pulsed ENDOR, and UV-vis spectroscopy. The experimental techniques indicate that the chiral bis(sulfoximine) ligand (S,S)-1 and the dienophile form a tetragonally distorted complex in CH(2)Cl(2). The ligand binds to the Cu(II) center via the imine nitrogens, whereas the dienophile interacts via the carbonyl oxygen atoms. The additional sites of the first coordination sphere are occupied by counterions and, presumably, solvent molecules. At the axial position, a triflate anion binds via an oxygen atom.
Publisher: Beilstein Institut
Date: 23-11-2022
Abstract: Cholesterol reacts under Appel conditions (CBr 4 /PPh 3 ) to give 3,5-cholestadiene (elimination) and 3 b -bromocholest-5-ene (substitution with retention of configuration). Thus, the bromination of cholesterol deviates from the stereochemistry of the standard Appel mechanism due to participation of the D 5 π -electrons. In contrast, the subsequent azidolysis (NaN 3 /DMF) of 3 b -bromocholest-5-ene proceeds predominantly by Walden inversion (S N 2) affording 3 a -azidocholest-5-ene. The structures of all relevant products were revealed by X-ray single crystal structure analyses, and the NMR data are in agreement to the reported ones. In light of these findings, we herein correct the previous stereochemical assignments reported by one of us in the Beilstein J. Org. Chem. 2015 , 11 , 1922–1932 and the Monatsh. Chem. 2018 , 149 , 505–517.
Publisher: Beilstein Institut
Date: 27-01-2023
DOI: 10.3762/BJOC.19.9
Abstract: Cholesterol reacts under Appel conditions (CBr 4 /PPh 3 ) to give 3,5-cholestadiene (elimination) and 3β-bromocholest-5-ene (substitution with retention of configuration). Thus, the bromination of cholesterol deviates from the stereochemistry of the standard Appel mechanism due to participation of the Δ 5 π-electrons. In contrast, the subsequent azidolysis (NaN 3 /DMF) of 3β-bromocholest-5-ene proceeds predominantly by Walden inversion (S N 2) affording 3α-azidocholest-5-ene. The structures of all relevant products were revealed by X-ray single crystal structure analyses, and the NMR data are in agreement to the reported ones. In light of these findings, we herein correct the previous stereochemical assignments reported by one of us in the Beilstein J. Org. Chem. 2015 , 11 , 1922–1932 and the Monatsh. Chem. 2018 , 149 , 505–517.
Location: United Kingdom of Great Britain and Northern Ireland
Location: Germany
Location: United States of America
No related grants have been discovered for David Talavera.