Enzyme Architecture: Breaking Down the Catalytic Cage that Activates Orotidine 5'-Monophosphate Decarboxylase for Catalysis.

ABSTRACT: We report the results of a study of the catalytic role of a network of four interacting amino acid side chains at yeast orotidine 5'-monophosphate decarboxylase ( ScOMPDC), by the stepwise replacement of all four side chains. The H-bond, which links the -CH₂OH side chain of S154 from the pyrimidine umbrella loop of ScOMPDC to the amide side chain of Q215 in the phosphodianion gripper loop, creates a protein cage for the substrate OMP. The role of this interaction in optimizing transition state stabilization from the dianion gripper side chains Q215, Y217, and R235 was probed by determining the kinetic parameter k_cat/ K_m for 16 enzyme variants, which include all combinations of single, double, triple, and quadruple S154A, Q215A, Y217F, and R235A mutations. T

SUBMITTER: Reyes AC 

PROVIDER: S-EPMC6317530 | biostudies-literature | 2018 Dec

REPOSITORIES: biostudies-literature