| EC |
1.14.99.38 |
| Accepted name: |
cholesterol 25-monooxygenase |
| Reaction: |
cholesterol + reduced acceptor + O2 = 25-hydroxycholesterol + acceptor + H2O |
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For diagram of cholic acid biosynthesis (sidechain), click here |
| Glossary: |
cholesterol = cholest-5-en-3β-ol |
| Other name(s): |
cholesterol 25-hydroxylase (ambiguous) |
| Systematic name: |
cholesterol,hydrogen-donor:oxygen oxidoreductase (25-hydroxylating) |
| Comments: |
Unlike most other sterol hydroxylases, this enzyme is not a cytochrome P-450. Instead, it uses diiron cofactors to catalyse the hydroxylation of hydrophobic substrates [1]. The diiron cofactor can be either Fe-O-Fe or Fe-OH-Fe and is bound to the enzyme through interactions with clustered histidine or glutamate residues [4,5]. In cell cultures, this enzyme down-regulates cholesterol synthesis and the processing of sterol regulatory element binding proteins (SREBPs). cf. EC 1.17.99.10, cholesterol C-25 hydroxylase. |
| Links to other databases: |
BRENDA, EXPASY, Gene, KEGG, MetaCyc, PDB, CAS registry number: 60202-07-5 |
| References: |
| 1. |
Lund, E.G., Kerr, T.A., Sakai, J., Li, W.P. and Russell, D.W. cDNA cloning of mouse and human cholesterol 25-hydroxylases, polytopic membrane proteins that synthesize a potent oxysterol regulator of lipid metabolism. J. Biol. Chem. 273 (1998) 34316–34327. [DOI] [PMID: 9852097] |
| 2. |
Chen, J.J., Lukyanenko, Y. and Hutson, J.C. 25-Hydroxycholesterol is produced by testicular macrophages during the early postnatal period and influences differentiation of Leydig cells in vitro. Biol. Reprod. 66 (2002) 1336–1341. [PMID: 11967195] |
| 3. |
Lukyanenko, Y., Chen, J.J. and Hutson, J.C. Testosterone regulates 25-hydroxycholesterol production in testicular macrophages. Biol. Reprod. 67 (2002) 1435–1438. [PMID: 12390873] |
| 4. |
Fox, B.G., Shanklin, J., Ai, J., Loehr, T.M. and Sanders-Loehr, J. Resonance Raman evidence for an Fe-O-Fe center in stearoyl-ACP desaturase. Primary sequence identity with other diiron-oxo proteins. Biochemistry 33 (1994) 12776–12786. [PMID: 7947683] |
| 5. |
Russell, D.W. The enzymes, regulation, and genetics of bile acid synthesis. Annu. Rev. Biochem. 72 (2003) 137–174. [DOI] [PMID: 12543708] |
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| [EC 1.14.99.38 created 2005, modified 2020] |
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