Interactions between solubilized cytochrome P-450 and hepatic microsomes.
Solubilized cytochrome P-450 has been prepared from the livers of 3-methylcholanthrene-pretreated rats. The enzyme preparation does not catalyze the monoxygenase reactions unless NADPH-cytochrome P-450 reductase and phospholipids are also present. Addition of solubilized cytochrome P-450 to rat liver microsomes increases the NADPH-dependent benzpyrene hydroxylase activity. The extent of the enhancement in catalytic activity is proportional to the amount of exogenous cytochrome P-450 bound to the microsomes. The microsomal bound exogenous cytochrome  P-450 can be enzymically reduced and hence is capable of catalyzing the oxygenation of benzpyrene. The addition of solubilized cytochrome P-450 also enhances the NADH-supported microsomal benzpyrene hydroxylation and the NADH synergism of the NADPH-supported reaction. It is proposed that the added cytochrome P-450 can be incorporated into the membrane and become a functional part of the microsomal monoxygenase system.
D000818:Animals; D001579:Benzopyrene Hydroxylase / Q000378:metabolism; D001665:Binding Sites; D003577:Cytochrome P-450 Enzyme System / Q000302:isolation & purification / Q000378:metabolism*; D004579:Electron Transport; D004789:Enzyme Activation; D008297:Male; D008862:Microsomes, Liver / Q000378:metabolism*; D009251:NADPH-Ferrihemoprotein Reductase / Q000378:metabolism; D011485:Protein Binding; D051381:Rats; D011955:Receptors, Drug; D012995:Solubility
D011955:Receptors, Drug; D003577:Cytochrome P-450 Enzyme System; D001579:Benzopyrene Hydroxylase; D009251:NADPH-Ferrihemoprotein Reductase