title: Hepatic mitochondrial cytochrome P-450: isolation and functional characterization.
abstract: A CO-binding heme protein was solubilized and partially purified from the inner membrane fraction of rat liver mitochondria by a modification of a method [Imai, Y. & Sato, R. (1974) Biochem. Biophys. Res. Commun. 60, 8-14] developed to purify cytochrome P-450 from liver microsomes. The partially purified preparation contained protoheme and its spectral properties are characteristic of the heme proteins of the cytochrome P-450 family. The isolated cytochrome P-450 preparation could reconstitute a CO-sensitive, NADPH-dependent 26-hydroxylation activity for 5beta-cholestane-3alpha,7alpha,-12alpha-triol when supplemented with NADPH-adrenodoxin reductase and adrenodoxin, both purified from bovine adrenocortical mitochondria. Unlike a cytochrome P-450 purified from liver microsomes of drug-untreated rats, however, the liver mitochondrial cytochrome P-450 could not catalyze NADPH-dependent benzphetamine N-demethylation in the presence of adrenodoxin reductase and adrenodoxin or function with the purified microsomal NADPH-cytochrome c reductase plus Emulgen 913 as an electron-donating system. It is concluded that the rat liver inner mitochondrial membrane houses a species of cytochrome P-450 functional in 5beta-cholestane-3alpha,7alpha,12alpha-triol 26-hydroxylation.
mesh_terms: D000818:Animals; D002248:Carbon Monoxide; D002777:Cholestanols; D003577:Cytochrome P-450 Enzyme System / Q000302:isolation & purification* / Q000378:metabolism; D007700:Kinetics; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology; D008930:Mitochondria, Liver / Q000201:enzymology*; D051381:Rats; D013057:Spectrum Analysis; D013250:Steroid Hydroxylases / Q000378:metabolism
chemical_list: D002777:Cholestanols; D002248:Carbon Monoxide; D003577:Cytochrome P-450 Enzyme System; D013250:Steroid Hydroxylases
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