title: [A shunted system of electron transport from NAD(P)H to cholesterol-hydroxylating cytochrome P-450 in adrenal cortex mitochondria].
abstract: The two main approaches presently used for cytochrome P-450scc modelling are as follows: i) the use of chemical compounds carrying activated oxygen species, e. g., peracids, organic hydroperoxides, iodosobenzene, etc., ii) the use of electrochemical reduction in the presence of redox-active compounds. In the present work, a new model system for simulation of steroidogenic electron transfer is proposed, which reduces cytochrome P-450 scc by NADPH in the absence of adrenodoxin reductase and adrenodoxin. Phenazine methosulfate is used as an electron carrier. More than 95% of cytochrome P-450scc is reduced in a model system. The reduction kinetics is characterized by a lag phase, thus indicating complex formation between cytochrome P-450scc and phenazine methosulfate or formation of intermediate reducing equivalents. NADH may also serve as an electron donor for cytochrome P-450scc. Phenazine methosulfate can reduce microsomal cytochrome P-450 LM2 and b5, but not cytochrome P-450 LM4. Superoxide dismutase does not affect the reduction, thus indicating that O9.- is not involved in the reduction process. The mechanism of hemoprotein reduction and the nature of intermediates which can be formed in the model system is proposed.
mesh_terms: D000302:Adrenal Cortex / Q000201:enzymology*; D000325:Adrenodoxin / Q000378:metabolism; D000818:Animals; D002417:Cattle; D002784:Cholesterol / Q000378:metabolism*; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D003573:Cytochrome b Group / Q000378:metabolism; D015786:Cytochromes b5; D004579:Electron Transport; D006900:Hydroxylation; D066298:In Vitro Techniques; D007700:Kinetics; D008928:Mitochondria / Q000201:enzymology*; D009249:NADP / Q000378:metabolism*; D010084:Oxidation-Reduction
chemical_list: D003573:Cytochrome b Group; D000325:Adrenodoxin; D009249:NADP; D015786:Cytochromes b5; D003577:Cytochrome P-450 Enzyme System; D002784:Cholesterol
vernacular_title: Shuntirovannaia sistema transporta élektronov s NAD(P)H na kholesteringidroksiliruiushchiĭ tsitokhrom P-450 mitokhondriĭ kory nadpochechnikov.