An examination of the relationship between active site loop size and thermodynamic activation parameters for orotidine 5'-monophosphate decarboxylase from mesophilic and thermophilic organisms.

ABSTRACT: Closure of the active site phosphate gripper loop of orotidine 5'-monophosphate decarboxylase from Saccharomyces cerevisiae (ScOMPDC) over the bound substrate orotidine 5'-monophosphate (OMP) activates the bound substrate for decarboxylation by at least 10(4)-fold [Amyes, T. L., Richard, J. P., and Tait, J. J. (2005) J. Am. Chem. Soc. 127, 15708-15709]. The 19-residue phosphate gripper loop of the mesophilic ScOMPDC is much larger than the nine-residue loop at the ortholog from the thermophile Methanothermobacter thermautotrophicus (MtOMPDC). This difference in loop size results in a small decrease in the total intrinsic phosphate binding energy of the phosphodianion group of OMP from 11.9 to 11.6 kcal/mol, along with a modest decrease in the extent of activation by phosphite dianion of de

SUBMITTER: Toth K 

PROVIDER: S-EPMC2754381 | biostudies-literature | 2009 Aug

REPOSITORIES: biostudies-literature