title: Subcellular localization and properties of the NAD(P)H oxidase from equine polymorphonuclear leukocytes.
abstract: The subcellular distribution of the superoxide-forming enzyme in horse polymorphonuclear leukocytes was investigated. After activation of the cells with sodium oleate, a relatively stable and NAD(P)H-dependent oxygen consumption and superoxide production was found in association with the plasma membranes. The pH dependence displayed an optimum near neutrality. The apparent Km values were 38 x 10(-6) mol/l for NADPH and 1,560 x 10(-6) mol/l for NADH, suggesting that NADPH is the physiological donor. The rates of oxygen uptake, O2- production, and NADP consumption were consistent with the stoichiometry: 2 O2 + NADPH leads to 2 O2- + NADP. The failure to demonstrate an increase of NAD(P)H-dependent oxidative activity in the cellular fractions that the investigated NADPH oxidase is identical with the enzyme responsible for the respiratory burst in phagocytizing leukocytes.
mesh_terms: D000818:Animals; D002451:Cell Compartmentation; D002462:Cell Membrane / Q000201:enzymology; D006736:Horses; D007700:Kinetics; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism*; D019255:NADPH Oxidases; D009504:Neutrophils / Q000201:enzymology*; D010101:Oxygen Consumption; D010587:Phagocytosis; D013481:Superoxides / Q000096:biosynthesis
chemical_list: D013481:Superoxides; D009247:NADH, NADPH Oxidoreductases; D019255:NADPH Oxidases