Hepatic mitochondrial cytochrome P-450: isolation and functional characterization

Proc Natl Acad Sci U S A. 1977 Dec;74(12):5477-81. doi: 10.1073/pnas.74.12.5477.


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.

Publication types

  • Comparative Study

MeSH terms

  • Animals
  • Carbon Monoxide
  • Cholestanols
  • Cytochrome P-450 Enzyme System / isolation & purification*
  • Cytochrome P-450 Enzyme System / metabolism
  • Kinetics
  • Male
  • Microsomes, Liver / enzymology
  • Mitochondria, Liver / enzymology*
  • Rats
  • Spectrum Analysis
  • Steroid Hydroxylases / metabolism


  • Cholestanols
  • Carbon Monoxide
  • Cytochrome P-450 Enzyme System
  • Steroid Hydroxylases