IUBMB Enzyme Nomenclature


Accepted name: sterol 14α-demethylase (ferredoxin)

Reaction: a 14α-methylsteroid + 6 reduced ferredoxin [iron-sulfur] cluster + 6 H+ + 3 O2 = a Δ14-steroid + formate + 6 oxidized ferredoxin [iron-sulfur] cluster + 4 H2O (overall reaction)
(1a) a 14α-methylsteroid + 2 reduced ferredoxin [iron-sulfur] cluster + 2 H+ + O2 = a 14α-hydroxymethylsteroid + 2 oxidized ferredoxin [iron-sulfur] cluster + H2O
(1b) a 14α-hydroxymethylsteroid + 2 reduced ferredoxin [iron-sulfur] cluster + 2 H+ + O2 = a 14α-formylsteroid + 2 oxidized ferredoxin [iron-sulfur] cluster + 2 H2O
(1c) a 14α-formylsteroid + 2 reduced ferredoxin [iron-sulfur] cluster + 2 H+ + O2 = a Δ14-steroid + formate + 2 oxidized ferredoxin [iron-sulfur] cluster + H2O

For diagram of reaction click here.

Other name(s): cyp51 (gene name)

Systematic name: sterol,reduced ferredoxin:oxygen oxidoreductase (14-methyl cleaving)

Comments: A cytochrome P-450 (heme-thiolate) protein found in several bacterial species. The enzyme, which is involved in sterol biosynthesis, 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. The enzyme from Methylococcus capsulatus is fused to the ferredoxin by an alanine-rich linker. cf. EC, sterol 14α-demethylase.

Links to other databases: BRENDA, EXPASY, ExplorEnz, KEGG, MetaCyc, CAS registry number:


1. Jackson, C.J., Lamb, D.C., Marczylo, T.H., Warrilow, A.G., Manning, N.J., Lowe, D.J., Kelly, D.E. and Kelly, S.L. A novel sterol 14α-demethylase/ferredoxin fusion protein (MCCYP51FX) from Methylococcus capsulatus represents a new class of the cytochrome P450 superfamily. J. Biol. Chem 277 (2002) 46959-46965. [PMID: 12235134]

2. Rezen, T., Debeljak, N., Kordis, D. and Rozman, D. New aspects on lanosterol 14α-demethylase and cytochrome P450 evolution: lanosterol/cycloartenol diversification and lateral transfer. J. Mol. Evol. 59 (2004) 51-58. [PMID: 15383907]

3. Desmond, E. and Gribaldo, S. Phylogenomics of sterol synthesis: insights into the origin, evolution, and diversity of a key eukaryotic feature. Genome Biol Evol 1 (2009) 364-381. [PMID: 20333205]

[EC created 2019]

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