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Ubiquinone‐5 is reduced by Superoxide in the aerobic state by NADPH oxidase of guinea pig macrophages
Author(s) -
Nakamura Michio,
Murakami Masakazu,
Umei Toshihiko,
Minakami Shigeki
Publication year - 1985
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(85)80711-0
Subject(s) - chemistry , superoxide , xanthine oxidase , semiquinone , superoxide dismutase , nadph oxidase , oxidase test , guinea pig , biochemistry , enzyme , phagocytosis , quinone , biology , microbiology and biotechnology , endocrinology
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 O 2 − 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 O 2 − but due to the accelerated dismutation of O 2 − which otherwise reduces the quinone. Molecular oxygens are therefore preferential electron acceptors in the NADPH oxidase even in the presence of Q1.