PMID: 6811268Jul 1, 1982

Hydroxylations in biosynthesis of bile acids. Cytochrome P-450 LM4 and 12alpha-hydroxylation of 5beta-cholestane-3alpha, 7alpha-diol

European Journal of Biochemistry
R Hansson, K Wikvall


12alpha-Hydroxylation of 5beta-cholestane-3alpha, 7alpha-diol was studied in reconstituted systems consisting of electrophoretically homogeneous cytochrome P-450 LM4 fractions and NADPH-cytochrome P-450 reductase from rabbit liver microsomes. Cytochrome P-450 LM4 fractions were prepared from untreated, phenobarbital-treated, beta-naphthoflavone-treated and starved rabbits. The purified cytochromes catalyzed 12alpha-hydroxylation more efficiently than the corresponding microsomes. In the reconstituted systems, carbon monoxide inhibited 12alpha-hydroxylation by 50-80%. The rate of 12alpha-hydroxylation was three to four times higher with cytochrome P-450 LM4 fractions from starved rabbits than with cytochrome P-450 LM4 fractions from untreated, phenobarbital-treated and beta-naphthoflavone-treated animals. Amino acid analyses, peptide mapping experiments as well as absorption spectral and circular dichroism spectral analyses revealed physical differences between cytochrome P-450 LM4 fractions from starved animals and preparations from phenobarbital-treated animals. The results indicate the presence of a cytochrome P-450 species in the cytochrome P-450 LM4 fraction specific for 12alpha-hydroxylation.


Oct 1, 1973·Biochemical and Biophysical Research Communications·C BernhardssonK Wikvall
Sep 30, 1974·Molecular and Cellular Biochemistry·I Björkhem, H Danielsson
Jul 1, 1974·Analytical Biochemistry·B PenkeK Kovács
Mar 12, 1968·Biochemical and Biophysical Research Communications·M SuzukiN B Myant
Nov 1, 1981·European Journal of Biochemistry·H BoströmK Wikvall


Dec 2, 2006·European Journal of Drug Metabolism and Pharmacokinetics·S KevresanM Mikov
Mar 4, 2020·The Journal of Heredity·Andrew P AndersonAdam G Jones
Dec 13, 1996·The Journal of Biological Chemistry·G EggertsenI Björkhem

Related Concepts

Bile Salts
Cytochrome P-450 Oxygenase
Microsomes, Liver
NADPH-Ferrihemoprotein Reductase

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