Pyridine nucleotide-dependent generation of hydrogen peroxide by a particulate fraction from human neutrophils: effect of substrate concentration.
NAD(P)H oxidase activity was determined in particulate fractions from human neutrophils by measuring the production of hydrogen peroxide. Activity was measured over a wide range of substrate concentrations from 0.0 to 4.0 mM. The activity with NADPH was consistently greater than with NADH. Activity towards both substrates was higher in a particulate fraction derived from cells which had phagocytized opsonized zymosan than in a corresponding fraction from resting cells. This increased activity was apparently due to a decreased Km of the enzyme, although no evidence of allosteric kinetics was obtained. The activity was markedly reduced in the presence of superoxide dismutase, indicating the involvement of a superoxide-mediated chain reaction. Particular fractions derived from cells of a patient with chronic granulomatous disease exhibited decreased activity towards both substrates and an apparent defect in the activation of the enzyme by phagocytosis.
D002458:Cell Fractionation; D003594:Cytoplasmic Granules / Q000378:metabolism; D005561:Formates / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism*; D009249:NADP / Q000378:metabolism*; D009504:Neutrophils / Q000378:metabolism*; D010587:Phagocytosis; D013482:Superoxide Dismutase / Q000494:pharmacology
D005561:Formates; D009249:NADP; D006861:Hydrogen Peroxide; D013482:Superoxide Dismutase