A flavoprotein [1, 2]. The enzyme from Escherichia coli is specific for NADPH and is most active with quinone derivatives and ferricyanide as electron acceptors .
Menaquinone can act as acceptor. The enzyme from hog liver is inhibited by dicoumarol and folic acid derivatives but not by 2,4-dinitrophenol .
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SYSTEMATIC NAME
IUBMB Comments
NADPH:(quinone-acceptor) oxidoreductase
A flavoprotein [1, 2]. The enzyme from Escherichia coli is specific for NADPH and is most active with quinone derivatives and ferricyanide as electron acceptors [3].
Menaquinone can act as acceptor. The enzyme from hog liver is inhibited by dicoumarol and folic acid derivatives but not by 2,4-dinitrophenol [1].
enzyme displays bifunctional 3alpha-hydroxysteroid dehydrogenase and NADPH reductase (quinone) activities. Quinone reduction occurs via a mechanism that differs from 3-ketosteroid reduction. In this mechanism, the electron donor NADPH and acceptor o-quinone are bound in close proximity, which permits hydride transfer without formal protonation of the acceptor carbonyl by Tyr 55
the pH dependency of 9,10-phenanthrenequinone reduction catalyzed by the wild-type enzyme is different to that observed for 3-ketosteroid reduction. The kcat value for 9,10-phenanthrenequinone reduction is pH-dependent with the maximal rate decreasing with increasing pH but reveals an ionizable group with a pKb of 8.90 that must be protonated for maximal activity
NADPH oxidase complex consists of membrane and cytosolic subunits. The gp91phox and p22phox are integral membrane proteins that form a heterodimeric flavocytochrome b558, the catalytic core of the enzyme
NADPH oxidase complex consists of membrane and cytosolic subunits. The gp91phox and p22phox are integral membrane proteins that form a heterodimeric flavocytochrome b558, the catalytic core of the enzyme
narrow substrate specificity, reduction of selected aromatic quinones and alpha-dicarbonyls. The activation energy for 9,10-phenanthrenequinone reduction is unchanged in Y55 mutants
narrow substrate specificity, reduction of selected aromatic quinones and alpha-dicarbonyls. The activation energy for 9,10-phenanthrenequinone reduction is unchanged in Y55 mutants
The natural compound ascorbigen modulates NADPH-quinone oxidoreductase (NQO1) mRNA and enzyme activity levels in cultured liver cells and in laboratory rats