title: Papain proteolysis releases a soluble NADPH dependent diaphorase activity from bovine neutrophil membranes.
abstract: An NADPH dependent cytochrome c reductase has been purified from resting bovine neutrophil membranes. A high degree of purification, approaching homogeneity, is indicated by the presence of a single 75 kDa protein band on silver stained SDS-PAGE (10%). The purified protein catalyzes as well an NADPH dependent reduction of iodonitrotetrazolium violet (INT). Limited papain digestion of the purified preparation produces a 65 kDa product which retains both enzymatic activities. In a similar fashion papain digestion of the plasma membrane bound protein generates a fully active soluble NADPH dependent INT and cytochrome c reductase preparation (65 kDa). Proteolytic cleavage would appear to occur at a protein-membrane anchor remote from the proteins catalytic site. The cytochrome c reductase acts independently of the O2-generating cytochrome b558, a leukocyte plasma membrane protein which also catalyzes an NADPH dependent INT reduction.
authors.affiliation: Department of Biochemistry and Biophysics, John A. Burns School of Medicine, University of Hawaii, Honolulu 96822, USA.
authors.forename: J
authors.initials: J
authors.lastname: Li
authors.forename: L M
authors.initials: LM
authors.lastname: Kon
authors.forename: R J
authors.initials: RJ
authors.lastname: Guillory
mesh_terms: D000818:Animals; D002417:Cattle; D002462:Cell Membrane / Q000378:metabolism; D003574:Cytochrome c Group / Q000378:metabolism; D008058:Dihydrolipoamide Dehydrogenase / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D009245:NADH Dehydrogenase / Q000302:isolation & purification* / Q000378:metabolism; D009249:NADP / Q000378:metabolism*; D009504:Neutrophils / Q000378:metabolism*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D010206:Papain / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000378:metabolism; D013778:Tetrazolium Salts / Q000378:metabolism
chemical_list: D003574:Cytochrome c Group; D008565:Membrane Proteins; D013778:Tetrazolium Salts; C013574:iodonitrotetrazolium; D009249:NADP; D013482:Superoxide Dismutase; D009245:NADH Dehydrogenase; D008058:Dihydrolipoamide Dehydrogenase; D010206:Papain; D010100:Oxygen