Ubiquinone-5 is reduced by superoxide in the aerobic state by NADPH oxidase of guinea pig macrophages.
The reduction of ubiquinone-5 (Q1) by the phagocytosis-specific NADPH oxidase of guinea pig macrophages was not inhibited by superoxide dismutase (SOD) at concentrations usually used for O2- assay but was inhibited at about 100-times higher concentrations. Titration of the reaction with SOD and a comparison with that of xanthine oxidase showed that the inhibition was not due to the semiquinone oxidation accelerated by a removal of O2- but due to the accelerated dismutation of O2- which otherwise reduces the quinone. Molecular oxygens are therefore preferential electron acceptors in the NADPH oxidase even in the presence of Q1.
Nakamura
M
M
Murakami
M
M
Umei
T
T
Minakami
S
S
D000332:Aerobiosis; D000818:Animals; D006224:Cricetinae; D003574:Cytochrome c Group / Q000378:metabolism; D007700:Kinetics; D008264:Macrophages / Q000201:enzymology*; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism*; D019255:NADPH Oxidases; D010101:Oxygen Consumption; D010587:Phagocytosis; D013482:Superoxide Dismutase / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism*; D014451:Ubiquinone / Q000378:metabolism*
D003574:Cytochrome c Group; D013481:Superoxides; D014451:Ubiquinone; D013482:Superoxide Dismutase; D009247:NADH, NADPH Oxidoreductases; D019255:NADPH Oxidases; C025203:Ubiquinone Q1