Enzymatic generation of alloxan radicals in rat liver microsomes: possible participation of reduced nicotinamide adenine dinucleotide phosphate (NADPH)-cytochrome P-450 reductase.
Electron spin resonance studies showed that addition of rat liver microsomes to the reaction system of alloxan with reduced nicotinamide adenine dinucleotide phosphate (NADPH) resulted in a marked increase in the generation of alloxan radicals (AH.), whereas heat-denatured microsomes were without such effect. Oxidation of NADPH by alloxan was also stimulated by microsomes. The microsomes from rats treated with phenobarbital, an inducer of cytochrome P-450 reductase, greatly stimulated both the AH.generation and the NADPH oxidation. However, the microsomes from rats treated with 3-methylcholanthrene, an inducer of DT-diaphorase, did not have stimulative effect greater than the control microsomes. These results suggest the possibility that NADPH-linked AH.generations in microsomal membranes is catalyzed by NADPH-cytochrome P-450 reductase.
Sakurai
K
K
Hokkaido Institute of Pharmaceutical Sciences, Otaru, Japan.
Haga
K
K
Ogiso
T
T
D000496:Alloxan / Q000378:metabolism*; D000818:Animals; D005609:Free Radicals; D007700:Kinetics; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology*; D009249:NADP / Q000378:metabolism; D009251:NADPH-Ferrihemoprotein Reductase / Q000378:metabolism*; D010084:Oxidation-Reduction; D051381:Rats; D011919:Rats, Inbred Strains
D005609:Free Radicals; D009249:NADP; D000496:Alloxan; D009251:NADPH-Ferrihemoprotein Reductase