Glucosinolate Biosynthesis (Further Characterization of the Aldoxime-Forming Microsomal Monooxygenases in Oilseed Rape Leaves).
Plant Physiol
; 109(1): 299-305, 1995 Sep.
Article
en En
| MEDLINE
| ID: mdl-12228596
ABSTRACT
The initial steps in glucosinolate biosynthesis are thought to proceed from amino acids, via N-hydroxy amino acids, to aldoximes. We showed previously that microsomes from green leaves of oilseed rape (Brassica napus cv Bienvenu) contain two distinct monooxygenases that catalyze the conversion of homophenylalanine and dihomomethionine to their respective aldoximes. Further characterization of these enzymes has now demonstrated that the latter enzyme catalyzes the NADPH-dependent oxidative decarboxylation of two higher homologs of methionine, in addition to dihomomethionine. No activity was found for either enzyme with L-methionine, DL-homomethionine, L-phenylalanine, L-tyrosine, or L-tryptophan. Both of these rape monooxygenase activities are dependent on O2, not requiring any other O2 species or radical. The presence of an unoxidized sulfur atom and its relative position in the side chain of the aliphatic substrates are important for binding to the active site of the methionine-homolog enzyme. Neither enzyme has any characteristics of a cytochrome P450-type enzyme, and antiserum raised against cytochrome P450 reductase did not significantly inhibit monooxygenase activity.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Idioma:
En
Revista:
Plant Physiol
Año:
1995
Tipo del documento:
Article
País de afiliación:
Reino Unido
Pais de publicación:
EEUU
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ESTADOS UNIDOS
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ESTADOS UNIDOS DA AMERICA
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EUA
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UNITED STATES
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UNITED STATES OF AMERICA
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US
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USA