Reaction: a 14α-methylsteroid + 3 [reduced NADPH—hemoprotein reductase] + 3 O2 = a Δ14-steroid + formate + 3 [oxidized NADPH—hemoprotein reductase] + 4 H2O (overall reaction)
(1a) a 14α-methylsteroid + [reduced NADPH—hemoprotein reductase] + O2 = a 14α-hydroxysteroid + [oxidized NADPH—hemoprotein reductase] + H2O
(1b) a 14α-hydroxysteroid + [reduced NADPH—hemoprotein reductase] + O2 = a 14α-formylsteroid + [oxidized NADPH—hemoprotein reductase] + 2 H2O
(1c) a 14α-formylsteroid + [reduced NADPH—hemoprotein reductase] + O2 = a Δ14-steroid + formate + [oxidized NADPH—hemoprotein reductase] + H2O
For diagram of reaction click here.
Glossary: obtusifoliol = 4α,14α-dimethyl-5α-ergosta-8,24(28)-dien-3β-ol or 4α,14α-dimethyl-24-methylene-5α-cholesta-8-en-3β-ol
Other name(s): obtusufoliol 14-demethylase; lanosterol 14-demethylase; lanosterol 14α-demethylase; sterol 14-demethylase; CYP51 (gene name); ERG11 (gene name)
Systematic name: sterol,[reduced NADPH—hemoprotein reductase]:oxygen oxidoreductase (14-methyl cleaving)
Comments: This cytochrome P-450 (heme-thiolate) enzyme acts on a range of steroids with a 14α-methyl group, such as obtusifoliol and lanosterol. The enzyme catalyses a hydroxylation and a reduction of the 14α-methyl group, followed by a second hydroxylation, resulting in the elimination of formate and formation of a 14(15) double bond.
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:
References:
1. Alexander, K., Akhtar, M., Boar, R.B., McGhie, J.F. and Barton, D.H.R. The removal of the 32-carbon atom as formic acid in cholesterol biosynthesis. J. Chem. Soc. Chem. Commun. (1972) 383-385.
2. Aoyama, Y. and Yoshida, Y. Different substrate specificities of lanosterol 14α-demethylase (P-45014DM) of Saccharomyces cerevisiae and rat liver of 24-methylene-24,25-dihydrolanosterol and 24,25-dihydrolanosterol. Biochem. Biophys. Res. Commun. 178 (1991) 1064-1071. [PMID: 1872829]
3. Aoyama, Y. and Yoshida, Y. The 4β-methyl group of substrate does not affect the activity of lanosterol 14α-demethylase (P45014DM) of yeast: differences between the substrate recognition by yeast and plant sterol 14α-demethylases. Biochem. Biophys. Res. Commun. 183 (1992) 1266-1272. [PMID: 1567403]
4. Bak, S., Kahn, R.A., Olsen, C.E. and Halkier, B.A. Cloning and expression in Escherichia coli of the obtusifoliol 14α-demethylase of Sorghum bicolor (L.) Moench, a cytochrome P450 orthologous to the sterol 14α-demethylases (CYP51) from fungi and mammals. Plant J. 11 (1997) 191-201. [PMID: 9076987]
5. Aoyama, Y. and Yoshida, Y. The 4β-methyl group of substrate does not affect the activity of lanosterol 14α-demethylase (P45014DM) of yeast: differences between the substrate recognition by yeast and plant sterol 14α-demethylases. Biochem. Biophys. Res. Commun. 183 (1992) 1266-1272. [PMID: 1567403]
6. Bak, S., Kahn, R.A., Olsen, C.E. and Halkier, B.A. Cloning and expression in Escherichia coli of the obtusifoliol 14α-demethylase of Sorghum bicolor (L.) Moench, a cytochrome P450 orthologous to the sterol 14α-demethylases (CYP51) from fungi and mammals. Plant J. 11 (1997) 191-201. [PMID: 9076987]