ORCID Profile
0000-0003-4270-6135
Current Organisation
University Of Strathclyde
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Publisher: Elsevier BV
Date: 10-2019
Publisher: Wiley
Date: 04-10-2011
Abstract: The thermodynamic effective molarities of a series of simple cycloalkenes, synthesised from α,ω-dienes by reaction with Grubbs' second generation precatalyst, have been evaluated. Effective molarities were measured from a series of small scale metathesis reactions and agreed well with empirical predictions derived from the number of rotors and the product ring strain. The use of electronic structure calculations (at the M06-L/6-311G** level of theory) was explored for predicting thermodynamic effective molarities in ring-closing metathesis. However, it was found that it was necessary to apply a correction to DFT-derived free energies to account for the entropic effects of solvation.
Publisher: Wiley
Date: 09-2002
DOI: 10.1046/J.1365-2958.2002.03109.X
Abstract: Zinc is essential but toxic in excess. Bacterial metallothionein, SmtA from Synechococcus PCC 7942, sequesters and detoxifies four zinc ions per molecule and contains a zinc finger structurally similar to eukaryotic GATA. The dearth of other reported bacterial metallothioneins has been surprising. Here we describe related bacterial metallothioneins (BmtA) from Anabaena PCC 7120, Pseudomonas aeruginosa and Pseudomonas putida that bind multiple zinc ions with high stability towards protons. Thiol modification demonstrates that cysteine coordinates zinc in all of these proteins. Additionally, (111)Cd-NMR, and (111)Cd-edited (1)H-NMR, identified histidine ligands in Anabaena PCC 7120 BmtA, analogous to SmtA. A related Escherichia coli protein bound only a single zinc ion, via four cysteine residues, with low stability towards protons (111)Cd-NMR and (111)Cd-edited (1)H-NMR confirmed exclusive cysteine-coordination, and these cysteine residues reacted rapidly with 5,5'-dithiobis-(2-nitrobenzoic acid). (1)H-NMR of proteins from P. aeruginosa, Anabaena PCC 7120 and E. coli generated fingerprints diagnostic for the GATA-like zinc finger fold of SmtA. These studies reveal first the existence of multiple bacterial metallothioneins, and second proteins with SmtA-like lone zinc fingers, devoid of a cluster,and designated GatA. We have identified 12 smtA-like genes in sequence databases including four of the gatA type.
Publisher: Proceedings of the National Academy of Sciences
Date: 07-08-2001
Abstract: Zinc is essential for many cellular processes, including DNA synthesis, transcription, and translation, but excess can be toxic. A zinc-induced gene, smtA , is required for normal zinc-tolerance in the cyanobacterium Synechococcus PCC 7942. Here we report that the protein SmtA contains a cleft lined with Cys-sulfur and His-imidazole ligands that binds four zinc ions in a Zn 4 Cys 9 His 2 cluster. The thiolate sulfurs of five Cys ligands provide bridges between the two ZnCys 4 and two ZnCys 3 His sites, giving two fused six-membered rings with distorted boat conformations. The inorganic core strongly resembles the Zn 4 Cys 11 cluster of mammalian metallothionein, despite different amino acid sequences, a different linear order of the ligands, and presence of histidine ligands. Also, SmtA contains elements of secondary structure not found in metallothioneins. One of the two Cys 4 -coordinated zinc ions in SmtA readily exchanges with exogenous metal ( 111 Cd), whereas the other is inert. The thiolate sulfur ligands bound to zinc in this site are buried within the protein. Regions of β-strand and α-helix surround the inert site to form a zinc finger resembling the zinc fingers in GATA and LIM-domain proteins. Eukaryotic zinc fingers interact specifically with other proteins or DNA and an analogous interaction can therefore be anticipated for prokaryotic zinc fingers. SmtA now provides structural proof for the existence of zinc fingers in prokaryotes, and sequences related to the zinc finger motif can be identified in several bacterial genomes.
Publisher: Elsevier BV
Date: 1993
DOI: 10.1016/0731-7085(93)80145-Q
Abstract: The application of 600 MHz two-dimensional J-resolved 1H NMR spectroscopy (JRES) to the analysis of human urine and blood plasma is demonstrated. This method when applied at very high field gives a rapid means of simplifying and aiding the assignment of highly overlapped resonances of minor metabolites in biofluids. Using this approach, mixtures of drug and endogenous metabolites were identified in untreated urine s les, the signals of which were extensively overlapped in single pulse 600 MHz spectra. For untreated blood plasma s les the JRES experiment was also effective for the selective attenuation of signals from the plasma proteins thus revealing strong well-resolved signals from the low molecular weight components. For the first time it was shown to be possible to assign in detail the spectra region from 3 to 4 ppm in blood plasma, including the complete assignment of the signals from alpha- and beta-glucose. JRES spectra of plasma were much easier to interpret and had a much higher information content than equivalent one-dimensional Hahn spin-echo spectra, thus aiding the identification of non protein-bound low molecular weight metabolites in plasma.
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2SC00630H
Publisher: Elsevier BV
Date: 03-1998
DOI: 10.1016/S0304-4165(97)00116-5
Abstract: High resolution 600 MHz 1H NMR spectroscopy was used to investigate the changes in biochemical composition of whole human seminal fluid (SF) and an artificial mixture of prostatic (PF) and seminal vesicle fluid (SVF). A variety of time-related biochemical changes were monitored simultaneously and non-invasively in SF, including enzymatic hydrolysis of phosphorylcholine to choline and polypeptides to amino acids. The fastest NMR-observable reactions in SF were the conversion of phosphorylcholine to choline (t1/2 approximately equal to 9 min) and uridine-5'-monophosphate (UMP) to uridine (t1/2 < 2 min). UMP has not previously been detected in SF because of its rapid hydrolysis. Artificial mixtures of separately obtained prostatic and SVF showed very similar biochemical changes to those observed in whole SF. Addition of EDTA to SF incubated for 2 min post ejaculation strongly inhibited peptide hydrolysis. Zn2+, present in whole SF was shown to be non EDTA-chelatable 2 min after ejaculation, whereas after 7 min, a singlet signal from the ethylenic protons of the Zn-EDTA2- complex was clearly observed which remained constant after 7 min. This indicates that soon after ejaculation (< 5 min) Zn2+ is immobilised in a macromolecular complex which is rapidly broken down by proteolytic enzymes, the released Zn2+ then being free to react with EDTA. Mg- and Ca-EDTA2- complexes were observed at 2 min and remained constant (at 1.4 and 2.1 mM, respectively) throughout the entire time course of the experiment. These studies cast new light on the time-related biochemical changes occurring in the post-ejaculatory SF which may have an important role in reproductive function.
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0SC01612H
Abstract: A tetrazincated ferrocene complex displays ergent basicity towards aromatic substrates through either its core or peripheral ligands.
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for John Andrew Parkinson.