The superoxide-generating system of human neutrophils possesses a novel diaphorase activity. Evidence for distinct regulation of electron flow within NADPH oxidase by p67-phox and p47-phox.
A dye reductase activity, independent of the production of superoxide, is induced in membranes prepared from stimulated human neutrophils or during activation of NADPH oxidase in a cell-free system. This diaphorase activity was greater under anaerobic as opposed to aerobic conditions. The activity has an absolute requirement for the membrane components of the oxidase, but does not appear to have an absolute dependence for the 47-kDa cytosolic factor p47-phox, suggesting the oxidase can be converted to a partial state of activation in the absence of this factor. The dye-reductase activity was inhibited at low concentration by the oxidase inhibitor, diphenylene iodonium. The electron acceptor, iodonitrotetrazolium violet (2-(4-iodophenyl)-3-(4-nitrophenyl)-5-phenyltetrazolium chloride) is both a substrate and a mixed inhibitor of NADPH oxidation.
Cross
A R
AR
Department of Molecular and Experimental Medicine, Scripps Research Institute, La Jolla, California 92037.
Yarchover
J L
JL
Curnutte
J T
JT
D000332:Aerobiosis; D000693:Anaerobiosis; D001713:Biphenyl Compounds / Q000494:pharmacology; D002474:Cell-Free System; D008058:Dihydrolipoamide Dehydrogenase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D006105:Granulomatous Disease, Chronic / Q000201:enzymology; D006801:Humans; D008566:Membranes / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases; D009252:NADPH Dehydrogenase / Q000378:metabolism; D019255:NADPH Oxidases; D009504:Neutrophils / Q000201:enzymology*; D009861:Onium Compounds / Q000494:pharmacology; D010084:Oxidation-Reduction; D010750:Phosphoproteins / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism*; D013778:Tetrazolium Salts / Q000378:metabolism
D001713:Biphenyl Compounds; D009861:Onium Compounds; D010750:Phosphoproteins; D013778:Tetrazolium Salts; C079789:neutrophil cytosol factor 67K; C031291:diphenyliodonium; D013481:Superoxides; C013574:iodonitrotetrazolium; D009247:NADH, NADPH Oxidoreductases; D019255:NADPH Oxidases; C060505:neutrophil cytosolic factor 1; D009252:NADPH Dehydrogenase; D008058:Dihydrolipoamide Dehydrogenase