TY - JOUR
T1 - Analysis of the roles of amino acid residues in the flavoprotein tryptophan 2-monooxygenase modified by 2-oxo-3-pentynoate
T2 - Characterization of His338, Cys339, and Cys511 mutant enzymes
AU - Sobrado, P.
AU - Fitzpatrick, P. F.
PY - 2002/6/1
Y1 - 2002/6/1
N2 - 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,
AB - 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,
KW - Flavoprotein
KW - Isotope effects
KW - L-amino acid oxidase
KW - Mutagenesis
KW - Oxidase
KW - Tryptophan monooxygenase
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U2 - 10.1016/S0003-9861(02)00063-2
DO - 10.1016/S0003-9861(02)00063-2
M3 - Article
C2 - 12051679
AN - SCOPUS:0036612879
VL - 402
SP - 24
EP - 30
JO - Archives of Biochemistry and Biophysics
JF - Archives of Biochemistry and Biophysics
SN - 0003-9861
IS - 1
ER -