Contrasting values of commitment factors measured from viscosity, pH, and kinetic isotope effects: Evidence for slow conformational changes in the D-amino acid oxidase reaction

Paul F. Fitzpatrick, Kevin A. Kurtz, John M. Denu, John F. Emanuele

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

The flavoprotein D-amino acid oxidase catalyzes the oxidation of D-amino acids to imino acids. Previous studies of pH and isotope effects on the reaction with D-alanine as substrate have established that the enzyme substrate complex partitions forward toward carbon-hydrogen bond cleavage 10 times as fast as the amino acid dissociates and that overall turnover is limited by product release. However, the V/K value for D-alanine is not affected by the solution viscosity, while the V(max) value is only 15% limited by diffusion. These results are interpreted as evidence for a protein conformational change between an open conformation which binds substrates and a closed complex within which catalysis occurs. Such a model is supported by the recently reported structure of the enzyme-benzoate complex (A. Mattevi, M.A. Vanoni, F. Todone, M. Rizzi, A. Teplyakov, A. Coda, M. Bolognesi, and B. Curti (1996) Proc. Natl. Acad. Sci. USA 93, 7496-7501).

Original languageEnglish (US)
Pages (from-to)100-109
Number of pages10
JournalBioorganic Chemistry
Volume25
Issue number2
DOIs
StatePublished - Apr 1997

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Drug Discovery
  • Organic Chemistry

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