Reactivity of cuprous stellacyanin as a quinone and semiquinone reductase.
Biochemistry
; 20(15): 4336-40, 1981 Jul 21.
Article
en En
| MEDLINE
| ID: mdl-6456762
ABSTRACT
The reactivity of cuprous stellacyanin as a quinone and semiquinone reductase has been examined. Rate constants (25.0 degrees C) measured for the oxidation of stellacyanin by 1,4-benzoquinone and benzosemiquinone are 2.3 X 10(4) M-1 s-1 (delta H not equal to = 4.4 kcal/mol, delta S not equal to = -24 eu) and 5.1 X 10(6) M-1 s-1, respectively [pH 7.0, I = 0.1 M (phosphate)]. The agreement of these rate constants with those calculated on the basis of relative Marcus theory is discussed. Stellacyanin is more effective than laccase in quenching benzosemiquinone, suggesting that the physiological role of this metalloprotein is to regulate the concentration of free radicals generated through the laccase-catalyzed oxidation of phenols.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Proteínas de Plantas
/
Quinona Reductasas
/
Metaloproteínas
/
NADH NADPH Oxidorreductasas
Idioma:
En
Revista:
Biochemistry
Año:
1981
Tipo del documento:
Article