IUBMB Enzyme Nomenclature


Accepted name: cholest-4-en-3-one 26-monooxygenase [(25R)-3-oxocholest-4-en-26-oate forming]

Reaction: cholest-4-en-3-one + 3 NADPH + 3 H+ + 3 O2 = (25R)-3-oxocholest-4-en-26-oate + 3 NADP+ + 4 H2O (overall reaction)
(1a) cholest-4-en-3-one + NADPH + H+ + O2 = (25R)-26-hydroxycholest-4-en-3-one + NADP+ + H2O
(1b) (25R)-26-hydroxycholest-4-en-3-one + NADPH + H+ + O2 = (25R)-26-oxocholest-4-en-3-one + NADP+ + 2 H2O
(1c) (25R)-26-oxocholest-4-en-3-one + NADPH + H+ + O2 = (25R)-3-oxocholest-4-en-26-oate + NADP+ + H2O

Other name(s): CYP142

Systematic name: cholest-4-en-3-one,NADPH:oxygen oxidoreductase [(25R)-3-oxocholest-4-en-26-oate forming]

Comments: This enzyme, found in several bacterial pathogens, is involved in degradation of the host cholesterol. It catalyses the hydroxylation of the C-26 carbon, followed by oxidation of the alcohol to the carboxylic acid via the aldehyde intermediate, initiating the degradation of the alkyl side-chain of cholesterol. The products are exclusively in the (25R) conformation. The enzyme also accepts cholesterol as a substrate. cf. EC, cholest-4-en-3-one 26-monooxygenase. The enzyme can receive electrons from ferredoxin reductase in vitro, its natural electron donor is not known yet.

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


1. Driscoll, M.D., McLean, K.J., Levy, C., Mast, N., Pikuleva, I.A., Lafite, P., Rigby, S.E., Leys, D. and Munro, A.W. Structural and biochemical characterization of Mycobacterium tuberculosis CYP142: evidence for multiple cholesterol 27-hydroxylase activities in a human pathogen. J. Biol. Chem. 285 (2010) 38270-38282. [PMID: 20889498]

2. Johnston, J.B., Ouellet, H. and Ortiz de Montellano, P.R. Functional redundancy of steroid C26-monooxygenase activity in Mycobacterium tuberculosis revealed by biochemical and genetic analyses. J. Biol. Chem. 285 (2010) 36352-36360. [PMID: 20843794]

[EC created 2016]

Return to EC 1.14.13 home page
Return to EC 1.14 home page
Return to EC 1 home page
Return to Enzymes home page
Return to IUBMB Biochemical Nomenclature home page