Role of a guanidinium cation-phosphodianion pair in stabilizing the vinyl carbanion intermediate of orotidine 5'-phosphate decarboxylase-catalyzed reactions.

ABSTRACT: The side chain cation of Arg235 provides a 5.6 and 2.6 kcal/mol stabilization of the transition states for orotidine 5'-monophosphate (OMP) decarboxylase (OMPDC) from Saccharomyces cerevisiae catalyzed reactions of OMP and 5-fluoroorotidine 5'-monophosphate (FOMP), respectively, a 7.2 kcal/mol stabilization of the vinyl carbanion-like transition state for enzyme-catalyzed exchange of the C-6 proton of 5-fluorouridine 5'-monophosphate (FUMP), but no stabilization of the transition states for enzyme-catalyzed decarboxylation of truncated substrates 1-(β-d-erythrofuranosyl)orotic acid and 1-(β-d-erythrofuranosyl) 5-fluorouracil. These observations show that the transition state stabilization results from formation of a protein cation-phosphodianion pair, and that there is no detectable stabil

SUBMITTER: Goryanova B 

PROVIDER: S-EPMC3838641 | biostudies-literature | 2013 Oct

REPOSITORIES: biostudies-literature