Reaction: 5β-cholestane-3α,7α,12α-triol + NADPH + H+ + O2 = (25R)-5β-cholestane-3α,7α,12α,26-tetraol + NADP+ + H2O
For diagram click here.
Other name(s): 5β-cholestane-3α,7α,12α-triol 26-hydroxylase; 5β-cholestane-3α,7α,12α-triol hydroxylase; cholestanetriol 26-hydroxylase; sterol 27-hydroxylase; sterol 26-hydroxylase; cholesterol 27-hydroxylase; CYP27A; CYP27A1; cytochrome P450 27A1'
Systematic name: 5β-cholestane-3α,7α,12α-triol,NADPH:oxygen oxidoreductase (26-hydroxylating)
Comments: Requires ferrodoxin. Acts on cholesterol, cholest-5-en-3β,7α-diol, 7α-hydroxycholest-4-en-3-one, 5β-cholestane-3α,7α-diol as well as 5β-cholestane-3α,7α,12α-triol. With cholesterol as well as 26-hydroxycholesterol, 24-hydroxy- and 25-hydroxycholesterol are also formed. With prolonged treatment, 26-hydroxycholesterol is converted into the corresponding 27-aldehyde and 27-oic acid.
Links to other databases: BRENDA, EXPASY, KEGG, CAS registry number: 52227-77-7
References:
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3. Andersson, S., Davis, D.L., Dahlbäck, H., Jörnvall, H. and Russell, D.W. Cloning, structure, and expression of the mitochondrial cytochrome P-450 sterol 26-hydroxylase, a bile acid biosynthetic enzyme. J. Biol. Chem. 264 (1989) 8222-8229. [PMID: 2722778]
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5. Furster, C., Bergman, T. and Wikvall, K. Biochemical characterization of a truncated form of CYP27A purified from rabbit liver mitochondria. Biochem. Biophys. Res. Commun. 263 (1999) 663-666. [PMID: 10512735]
6. Holmberg-Betsholtz, I., Lund, E., Björkhem, I. and Wikvall, K. Sterol 27-hydroxylase in bile acid biosynthesis. Mechanism of oxidation of 5β-cholestane-3α,7α,12α,27-tetrol into 3α,7α,12α-trihydroxy-5β-cholestanoic acid. J. Biol. Chem. 268 (1993) 11079-11085. [PMID: 8496170]
7. Pikuleva, I.A., Puchkaev, A. and Björkhem, I. Putative helix F contributes to regioselectivity of hydroxylation in mitochondrial cytochrome P450 27A1. Biochemistry 40 (2001) 7621-7629. [PMID: 11412116]