Analysis of the roles of amino acid residues in the flavoprotein tryptophan 2-monooxygenase modified by 2-oxo-3-pentynoate: Characterization of His338, Cys339, and Cys511 mutant enzymes

P. Sobrado, P. F. Fitzpatrick

Research output: Contribution to journalArticle

8 Scopus citations

Abstract

The flavoprotein tryptophan 2-monooxygenase catalyzes the oxidative decarboxylation of tryptophan to indoleacetamide. His338, Cys339, and Cys511 of the Pseudomonas savastanoi enzyme were previously identified as possible active-site residues by modification with 2-oxo-3-pentynoate ([G. Gadda, L.J. Dangott, W.H. Johnson Jr., C.P. Whitman, P.F. Fitzpatrick, Biochemistry 38 (1999) 5822-5828]). The H338N, C339A, and C511S enzymes have been characterized to determine the roles of these residues in catalysis. The steady-state kinetic parameters with both tryptophan and methionine decrease only slightly in the case of the H338N and C339A enzymes; the decrease in activity is greater for the C511S enzyme. Only in the case of the C511S enzyme do deuterium kinetic isotope effects on kinetic parameters indicate a significant change in catalytic rates. The structural bases for the effects of the mutations can be interpreted by identification of L-amino acid oxidase and tryptophan monooxygenase as homologous proteins,

Original languageEnglish (US)
Pages (from-to)24-30
Number of pages7
JournalArchives of Biochemistry and Biophysics
Volume402
Issue number1
DOIs
StatePublished - Jun 1 2002

Keywords

  • Flavoprotein
  • Isotope effects
  • L-amino acid oxidase
  • Mutagenesis
  • Oxidase
  • Tryptophan monooxygenase

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology

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