Nicotinamide adenine dinucleotide and nicotinamide adenine dinucleotide phosphate-dependent reduction of mammalian hepatic microsomal cytochrome b5: some properties of the enzyme system catalyzing the endogenous reduction of pyridine nucleotides.
1. An enzyme system is present in mouse hepatic microsomes which is capable of reducing NAD+ and NADP+ and, consequently, of reducing cytochrome b5 in the absence of other externally added cofactors. 2. A similar enzyme system is also present in hepatic microsomes of rat and rabbit. 3. The rates of reduction of cytochrome b5 and auto-oxidation of reduced cytochrome b5 were, however, much slower in NAD+ supplemented reaction media than in those supplemented with NADH. 4. The effects of sulfhydryl reagents, chelating agents and divalent cations are reported.
D000818:Animals; D002413:Cations, Divalent; D002614:Chelating Agents / Q000494:pharmacology; D003579:Cytochrome Reductases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D003573:Cytochrome b Group / Q000378:metabolism*; D042966:Cytochrome-B(5) Reductase; D015786:Cytochromes b5; D007700:Kinetics; D008297:Male; D051379:Mice; D008862:Microsomes, Liver / Q000378:metabolism*; D009243:NAD / Q000378:metabolism*; D009249:NADP / Q000378:metabolism*; D010084:Oxidation-Reduction; D011817:Rabbits; D051381:Rats; D011919:Rats, Inbred Strains; D013439:Sulfhydryl Reagents / Q000494:pharmacology
D002413:Cations, Divalent; D002614:Chelating Agents; D003573:Cytochrome b Group; D013439:Sulfhydryl Reagents; D009243:NAD; D009249:NADP; D015786:Cytochromes b5; D003579:Cytochrome Reductases; D042966:Cytochrome-B(5) Reductase