- Michael acceptor-containing coenzyme a analogues as inhibitors of the atypical coenzyme a disulfide reductase from staphylococcus aureus
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Coenzyme A (CoA) analogues containing α,β-unsaturated ester, ketone, and sulfone moieties were prepared by chemo-enzymatic synthesis as inhibitors of coenzyme A disulfide reductase (CoADR), a proven and as yet unexploited drug target in Staphylococcus aureus. Among these Michael acceptor-containing CoA analogues, which were designed to target CoADR's single essential active site cysteine for conjugate addition, a phenyl vinyl sulfone-containing analogue showed the most potent inhibition with a competitive Ki of ~40 nM, and time-dependent inactivation with a second-order rate of inactivation constant of ~40 000 s -1?M-1. Our results suggest that electrophilic substrate analogues should be considered as potential inhibitors of other medicinally relevant disulfide reductase enzymes.
- Van Der Westhuyzen, Renier,Strauss, Erick
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supporting information; experimental part
p. 12853 - 12855
(2010/11/05)
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- Kinetics and Equilibria of Thiol/Disulfide Interchange Reactions of Selected Biological Thiols and Related Molecules with Oxidized Glutathione
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Rate constants for reaction of coenzyme A and cysteine with oxidized glutathione (GSSG) and equilibrium constants for the reaction of coenzyme A, cysteine, homocysteine, cysteamine, and related thiols with GSSG by thiol/disulfide interchange were determined over a range of pD values by NMR spectroscopy.The rate constants for reaction of the thiolate anion forms of coenzyme A and cysteine with GSSG suggest that reduction of GSSG by coenzyme A and cysteine is a mechanistically uncomplicated SN2 reaction.Equilibrium constants for the thiol/disulfide interchange reactions show a strong dependence on the Bronsted basicity of the thiolate anion.In a similar way, ΔE0', the difference between the half-cell potentials for the RSSR/RSH and GSSG/GSH redox couples, is linearly dependent on the difference between the pKA values of RSH and glutathione: ΔE0' = 64ΔpKA - 7.7 where ΔE0' is in units of mV.The reducing strength at a given pH is also determined by the fraction of the thiol present in the reactive thiolate form.At pD 7, the half-cell potentials for coenzyme A, cysteine, homocysteine, and cysteamine are close to that of glutathione, the major intracellular thiol redox system, which suggests that small changes in the intracellular redox potential can cause significant changes in the intracellular distribution of these biological thiols between their reduced and oxidized forms.
- Keire, David A.,Strauss, Erin,Guo, Wei,Noszal, Bela,Rabenstein, Dallas L.
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p. 123 - 127
(2007/10/02)
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- N6-[N-(6-Aminohexyl)carbamoylmethyl]-coenzyme A. Synthesis and application in affinity chromatography and as an immobilized active coenzyme.
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The synthesis of a new coenzyme A analogue, N6-[N-(6-aminohexyl)carbamoylmethyl]-CoA, suitable for immobilisation through its terminal amino group to support matrices, is described. The synthetic route starts with bis(CoA) and involves the following steps: alkylation with iodoacetic acid and rearrangement yielding bis(N6-carboxymethyl-CoA), elongation of the carboxymethyl terminal with 1,6-diaminohexane using carbodiimide to yield bis(N6-[N-(6-aminohexyl)-carbamoylmethyl]-CoA) and finally the splitting of this bis[CoA analogue) through reduction with dithiothreitol to give the final product in approximately 10% overall yield. This CoA analogue showed 'coenzymic activity' with the enzymes acetyl-CoA synthetase, phosphotransacetylase and succinic thiokinase. Covalent binding of the CoA analogue to Sepharose 4B was normally carried out using its S-(5-thio-2-nitrobenzoic acid) derivative as this allows a convenient way for determining the amount of ligand coupled, based on the amount of 5-thio-2-nitrobenzoic acid liberated from the gel after reduction with dithiothreitol. After covalent binding of the CoA analogue to water-soluble activated dextran 70, the analogue was recycled while present in an ultrafiltration cell using the enzymes phosphotransacetylase and citrate synthase. The reaction was followed by measuring the citrate formed on addition of acetylphosphate and oxaloacetate. In affinity chromatographic studies it was shown that the CoA-Sepharose preparation could bind the CoA-dependent enzymes citrate synthase and succinic thiokinase and these could be biospecifically eluted using soluble CoA.
- Rieke,Barry,Mosbach
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p. 203 - 212,205, 206
(2007/10/10)
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