Dissecting the total transition state stabilization provided by amino acid side chains at orotidine 5'-monophosphate decarboxylase: a two-part substrate approach

Biochemistry. 2008 Jul 29;47(30):7785-7. doi: 10.1021/bi800939k. Epub 2008 Jul 4.

Abstract

Kinetic analysis of decarboxylation catalyzed by S154A, Q215A, and S154A/Q215A mutant yeast orotidine 5'-monophosphate decarboxylases with orotidine 5'-monophosphate (OMP) and with a truncated nucleoside substrate (EO) activated by phosphite dianion shows (1) the side chain of Ser-154 stabilizes the transition state through interactions with the pyrimidine rings of OMP or EO, (2) the side chain of Gln-215 interacts with the phosphodianion group of OMP or with phosphite dianion, and (3) the interloop hydrogen bond between the side chains of Ser-154 and Gln-215 orients the amide side chain of Gln-215 to interact with the phosphodianion group of OMP or with phosphite dianion.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Amino Acids / chemistry*
  • Amino Acids / metabolism
  • Binding Sites
  • Crystallography, X-Ray
  • Hydrogen Bonding
  • Kinetics
  • Models, Biological
  • Molecular Structure
  • Orotidine-5'-Phosphate Decarboxylase / chemistry*
  • Orotidine-5'-Phosphate Decarboxylase / metabolism
  • Substrate Specificity
  • Uridine Monophosphate / analogs & derivatives*
  • Uridine Monophosphate / chemistry
  • Uridine Monophosphate / metabolism

Substances

  • Amino Acids
  • uridine 5'-hexadecylphosphate
  • orotidylic acid
  • Uridine Monophosphate
  • Orotidine-5'-Phosphate Decarboxylase