EC 1 - Oxidoreductases
EC 1.14 - Acting on paired donors, with incorporation or reduction of molecular oxygen. The oxygen incorporated need not be derived from O2
EC 1.14.15 - With reduced iron-sulfur protein as one donor, and incorporation of one atom of oxygen
EC 1.14.15.6 - Cholesterol monooxygenase (side-chain-cleaving)
IntEnz view
ENZYME view
IntEnz Enzyme Nomenclature
EC 1.14.15.6
Names
Accepted name:
cholesterol monooxygenase (side-chain-cleaving)
Other
names:
C27-side chain cleavage enzyme
cholesterol 20-22-desmolase
cholesterol C20-22 desmolase
cholesterol desmolase
cholesterol side-chain cleavage enzyme
cholesterol side-chain-cleaving enzyme
cytochrome P-450scc
desmolase, steroid 20-22
enzymes, cholesterol side-chain-cleaving
steroid 20-22 desmolase
steroid 20-22-lyase
cytochrome p450scc
CYP11A1
cholesterol 20-22-desmolase
cholesterol C20-22 desmolase
cholesterol desmolase
cholesterol side-chain cleavage enzyme
cholesterol side-chain-cleaving enzyme
cytochrome P-450scc
desmolase, steroid 20-22
enzymes, cholesterol side-chain-cleaving
steroid 20-22 desmolase
steroid 20-22-lyase
cytochrome p450scc
CYP11A1
Systematic name:
cholesterol,reduced-adrenodoxin:oxygen oxidoreductase (side-chain-cleaving)
Reactions
- (1) cholesterol + 6 reduced adrenodoxin + 3 O2 + 6 H+ = pregnenolone + 4-methylpentanal + 6 oxidized adrenodoxin + 4 H2O
- (1a) cholesterol + 2 reduced adrenodoxin + O2 + 2 H+ = (22R)-22-hydroxycholesterol + 2 oxidized adrenodoxin + H2O
- (1b) (22R)-22-hydroxycholesterol + 2 reduced adrenodoxin + O2 + 2 H+ = (20R,22R)-20,22-dihydroxycholesterol + 2 oxidized adrenodoxin + H2O
- (1c) (20R,22R)-20,22-dihydroxy-cholesterol + 2 reduced adrenodoxin + O2 + 2 H+ = pregnenolone + 4-methylpentanal + 2 oxidized adrenodoxin + 2 H2O
Cofactor
Comments:
A heme-thiolate protein (cytochrome P450). The reaction proceeds in three stages, with two hydroxylations at C-22 and C-20 preceding scission of the side-chain between carbons 20 and 22. The initial source of the electrons is NADPH, which transfers the electrons to the adrenodoxin via EC 1.18.1.6, adrenodoxin-NADP+ reductase.
Links to other databases
Protein domains and families:
PROSITE:PDOC00081
Gene Ontology:
GO:0008386
CAS Registry Number:
37292-81-2
References
-
Mass spectrometric study of the enzymatic conversion of cholesterol to (22R)-22-hydroxycholesterol, (20R,22R)-20,22-dihydroxycholesterol, and pregnenolone, and of (22R)-22-hydroxycholesterol to the lgycol and pregnenolone in bovine adrenocortical preparations. Mode of oxygen incorporation.J. Biol. Chem. 250 : 9028-9037 (1975). [PMID: 1238395]
-
Adrenal mitochondrial cytochrome P-450scc. Cholesterol and adrenodoxin interactions at equilibrium and during turnover.J. Biol. Chem. 256 : 4321-4328 (1981). [PMID: 7217084]
-
Stoichiometry of mitochondrial cytochromes P-450, adrenodoxin and adrenodoxin reductase in adrenal cortex and corpus luteum. Implications for membrane organization and gene regulation.Eur. J. Biochem. 157 : 27-31 (1986). [PMID: 3011431]
-
Structural basis for pregnenolone biosynthesis by the mitochondrial monooxygenase system.Proc. Natl. Acad. Sci. U.S.A. 108 : 10139-10143 (2011). [PMID: 21636783]
-
Structural basis for three-step sequential catalysis by the cholesterol side chain cleavage enzyme CYP11A1.J. Biol. Chem. 286 : 5607-5613 (2011). [PMID: 21159775]
[EC 1.14.15.6 created 1983, modified 2013, modified 2014]