Cholestanetriol 26-monooxygenase

Cholestanetriol 26-monooxygenase

In enzymology, a cholestanetriol 26-monooxygenase is an enzyme that catalyzes the chemical reaction

5beta-cholestane-3alpha,7alpha,12alpha-triol + NADPH + H+ + O2 rightleftharpoons (25R)-5beta-cholestane-3alpha,7alpha,12alpha,26-tetraol + NADP+ + H2O

The 4 substrates of this enzyme are 5beta-cholestane-3alpha,7alpha,12alpha-triol, NADPH, H+, and O2, whereas its 3 products are (25R)-5beta-cholestane-3alpha,7alpha,12alpha,26-tetraol, NADP+, and H2O.

This enzyme belongs to the family of oxidoreductases, specifically those acting on paired donors, with O2 as oxidant and incorporation or reduction of oxygen. The oxygen incorporated need not be derived from O2 with NADH or NADPH as one donor, and incorporation of one atom o oxygen into the other donor. The systematic name of this enzyme class is 5beta-cholestane-3alpha,7alpha,12alpha-triol,NADPH:oxygen oxidoreductase (26-hydroxylating). Other names in common use include 5beta-cholestane-3alpha,7alpha,12alpha-triol 26-hydroxylase, 5beta-cholestane-3alpha,7alpha,12alpha-triol hydroxylase, cholestanetriol 26-hydroxylase, sterol 27-hydroxylase, sterol 26-hydroxylase, cholesterol 27-hydroxylase, CYP27A, CYP27A1, and cytochrome P450 27A1'. This enzyme participates in bile acid biosynthesis and ppar signaling pathway.


  • Okuda K, Hoshita N "Oxidation of 5-beta-cholestane-3 alpha, 7 alpha, 12 alpha-triol by rat-liver mitochondria". Biochim. Biophys. Acta. 164 381–8.
  • Wikvall K "Hydroxylations in biosynthesis of bile acids. Isolation of a cytochrome P-450 from rabbit liver mitochondria catalyzing 26-hydroxylation of C27-steroids". J. Biol. Chem. 259 3800–4.
  • Andersson S, Davis DL, Dahlback H, Jornvall H, Russell DW "Cloning, structure, and expression of the mitochondrial cytochrome P-450 sterol 26-hydroxylase, a bile acid biosynthetic enzyme". J. Biol. Chem. 264 8222–9.
  • Usui E, Noshiro M, Okuda K "Molecular cloning of cDNA for vitamin D3 25-hydroxylase from rat liver mitochondria". FEBS. Lett. 262 135–8.
  • Furster C, Bergman T, Wikvall K "Biochemical characterization of a truncated form of CYP27A purified from rabbit liver mitochondria". Biochem. Biophys. Res. Commun. 263 663–6.
  • Holmberg-Betsholtz I, Lund E, Bjorkhem I, Wikvall K "Sterol 27-hydroxylase in bile acid biosynthesis. Mechanism of oxidation of 5 beta-cholestane-3 alpha,7 alpha,12 alpha,27-tetrol into 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestanoic acid". J. Biol. Chem. 268 11079–85.
  • Pikuleva IA, Puchkaev A, Bjorkhem I "Putative helix F contributes to regioselectivity of hydroxylation in mitochondrial cytochrome P450 27A1". Biochemistry. 40 7621–9.

External links

The CAS registry number for this enzyme class is .

Gene Ontology (GO) codes

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