NADPH-dependent superoxide-forming oxidase in phagocytic vesicles of human monocytes.
Phagocytic vesicles with superoxide-forming NADPH oxidase activity were obtained from human monocytes phagocytosing oil droplets. The superoxide-forming activity in the monocyte vesicles increased for the first 5 min during incubation with oil droplets and remained constant for 30 min. NADPH-dependent activities of 2,6-dichlorophenol-indophenol (DCIP) reduction and ubiquinone-1 (Q1) reduction were found in the vesicles and the activities were closely associated with the superoxide-forming oxidase. The values of apparent Km for NADPH of these three activities were essentially the same and the activities were inhibited with a similar pattern by p-chloromercuribenzoate and a cationic detergent, cetyltrimethylammonium bromide. The activities were extremely labile and the DCIP reductase activity was most labile. The superoxide-forming oxidase and the Q1 reductase could be extracted with a mixture of deoxycholate and Tween-20. The extracted activities were not enhanced by the addition of FAD.
D015086:2,6-Dichloroindophenol / Q000097:blood; D002384:Catalysis; D003902:Detergents / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D009000:Monocytes / Q000201:enzymology*; D009247:NADH, NADPH Oxidoreductases / Q000097:blood*; D019255:NADPH Oxidases; D009504:Neutrophils / Q000201:enzymology; D010587:Phagocytosis; D013347:Subcellular Fractions / Q000201:enzymology; D014451:Ubiquinone / Q000097:blood
D003902:Detergents; D014451:Ubiquinone; D015086:2,6-Dichloroindophenol; D009247:NADH, NADPH Oxidoreductases; D019255:NADPH Oxidases; C022709:superoxide-forming enzyme; C025203:Ubiquinone Q1