97879-00-0Relevant academic research and scientific papers
Biomimetic Models for Cysteine Proteases. 1. Intramolecular Imidazole Catalysis of Thiol Ester Solvolysis: A Model for the Deacylation Step
Street, J. P.,Brown, R. S.
, p. 6084 - 6089 (2007/10/02)
The solvolysis of 2--4,5-dimethylimidazole (3) has been studied in ethanol-water solution as a model for the thiol ester intermediates occurring during the catalytic cycle of cysteine proteases.Additionally the solvolyses of N-acetyl-4,5-dimethyl-2-phenylimidazole (4) and benzenethiolacetate (5) were studied as reference compounds.At neutrality, a plateau in the pH-log kobsdprofile for solvolysis of 3 is seen due to the participation of imidazole.Evidence is given that the mechanism in this region is intramolecular general-base-catalyzed solvent attack on the thiol ester by imidazole.At pHs greater than 10, specific-base-catalyzed solvolysis of the thiol ester becomes predominant.There is no kinetic importance of an S-to-N acyl transfer during the course of solvolysis.The relevance of these results to the chemical mechanism of cysteine proteases is discussed.
