Investigating the role of a backbone to substrate hydrogen bond in OMP decarboxylase using a site-specific amide to ester substitution.

ABSTRACT: Hydrogen bonds between backbone amide groups of enzymes and their substrates are often observed, but their importance in substrate binding and/or catalysis is not easy to investigate experimentally. We describe the generation and kinetic characterization of a backbone amide to ester substitution in the orotidine 5'-monophosphate (OMP) decarboxylase from Methanobacter thermoautotrophicum (MtOMPDC) to determine the importance of a backbone amide-substrate hydrogen bond. The MtOMPDC-catalyzed reaction is characterized by a rate enhancement (∼10(17)) that is among the largest for enzyme-catalyzed reactions. The reaction proceeds through a vinyl anion intermediate that may be stabilized by hydrogen bonding interaction between the backbone amide of a conserved active site serine residue (Ser-127

SUBMITTER: Desai BJ 

PROVIDER: S-EPMC4210302 | biostudies-literature | 2014 Oct

REPOSITORIES: biostudies-literature