Copper,zinc superoxide dismutase as a univalent NO(-) oxidoreductase and as a dichlorofluorescin peroxidase.
J Biol Chem
; 276(38): 35253-7, 2001 Sep 21.
Article
en En
| MEDLINE
| ID: mdl-11461912
Nitroxyl (NO(-)) may be produced by nitric-oxide synthase and by the reduction of NO by reduced Cu,Zn-SOD. The ability of NO(-) to cause oxidations and of SOD to inhibit such oxidations was therefore explored. The decomposition of Angeli's salt (AS) produces NO(-) and that in turn caused the aerobic oxidation of NADPH, directly or indirectly. O(2) was produced concomitant with the aerobic oxidation of NADPH by AS, as evidenced by the SOD-inhibitable reduction of cytochrome c. Both Cu,Zn-SOD and Mn-SOD inhibited the aerobic oxidation of NADPH by AS, but the amounts required were approximately 100-fold greater than those needed to inhibit the reduction of cytochrome c. This inhibition was not due to a nonspecific protein effect or to an effect of those large amounts of the SODs on the rate of decomposition of AS. NO(-) caused the reduction of the Cu(II) of Cu,Zn-SOD, and in the presence of O(2), SOD could catalyze the oxidation of NO(-) to NO. The reverse reaction, i.e. the reduction of NO to NO(-) by Cu(I),Zn-SOD, followed by the reaction of NO(-) with O(2) would yield ONOO(-) and that could explain the oxidation of dichlorofluorescin (DCF) by Cu(I),Zn-SOD plus NO. Cu,Zn-SOD plus H(2)O(2) caused the HCO(3)(-)-dependent oxidation of DCF, casting doubt on the validity of using DCF oxidation as a reliable measure of intracellular H(2)O(2) production.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Oxidorreductasas
/
Peroxidasas
/
Superóxido Dismutasa
Límite:
Animals
/
Humans
Idioma:
En
Revista:
J Biol Chem
Año:
2001
Tipo del documento:
Article
País de afiliación:
Estados Unidos
Pais de publicación:
Estados Unidos