7alpha-hydroxycholest-4-en-3-one 12alpha-hydroxylase

In enzymology, a 7alpha-hydroxycholest-4-en-3-one 12alpha-hydroxylase (EC 1.14.13.95) is an enzyme that catalyzes the chemical reaction

7alpha-hydroxycholest-4-en-3-one + NADPH + H⁺ + O₂ ${\displaystyle \rightleftharpoons }$ 7alpha,12alpha-dihydroxycholest-4-en-3-one + NADP⁺ + H₂O

The 4 substrates of this enzyme are 7alpha-hydroxycholest-4-en-3-one (7 alpha-hydroxy-4-cholesten-3-one, NADPH, H⁺, and O₂, whereas its 3 products are , 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 7alpha-hydroxycholest-4-en-3-one,NADPH:oxygen oxidoreductase (12alpha-hydroxylating).

This enzymatic activity is performed by CYP8B1.^[1]

Other names used include 7alpha-hydroxy-4-cholesten-3-one 12alpha-monooxygenase, CYP12, sterol 12alpha-hydroxylase (ambiguous), and HCO 12alpha-hydroxylase. This enzyme participates in .

References[]

• Ishida H, Noshiro M, Okuda K, Coon MJ (October 1992). "Purification and characterization of 7 alpha-hydroxy-4-cholesten-3-one 12 alpha-hydroxylase". The Journal of Biological Chemistry. 267 (30): 21319–23. PMID 1400444.
• Eggertsen G, Olin M, Andersson U, Ishida H, Kubota S, Hellman U, Okuda KI, Björkhem I (December 1996). "Molecular cloning and expression of rabbit sterol 12alpha-hydroxylase". The Journal of Biological Chemistry. 271 (50): 32269–75. doi:10.1074/jbc.271.50.32269. PMID 8943286.
• Russell DW (2003). "The enzymes, regulation, and genetics of bile acid synthesis". Annual Review of Biochemistry. 72: 137–74. doi:10.1146/annurev.biochem.72.121801.161712. PMID 12543708.