| EC |
1.1.1.145 |
| Accepted name: |
3β-hydroxy-Δ5-steroid dehydrogenase |
| Reaction: |
a 3β-hydroxy-Δ5-steroid + NAD+ = a 3-oxo-Δ5-steroid + NADH + H+ |
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For diagram of cholesterol catabolism (rings a, B and c), click here |
| Other name(s): |
progesterone reductase; Δ5-3β-hydroxysteroid dehydrogenase; 3β-hydroxy-5-ene steroid dehydrogenase; 3β-hydroxy steroid dehydrogenase/isomerase; 3β-hydroxy-Δ5-C27-steroid dehydrogenase/isomerase; 3β-hydroxy-Δ5-C27-steroid oxidoreductase; 3β-hydroxy-5-ene-steroid oxidoreductase; steroid-Δ5-3β-ol dehydrogenase; 3β-HSDH; 5-ene-3-β-hydroxysteroid dehydrogenase; 3β-hydroxy-5-ene-steroid dehydrogenase |
| Systematic name: |
3β-hydroxy-Δ5-steroid:NAD+ 3-oxidoreductase |
| Comments: |
This activity is found in several bifunctional enzymes that catalyse the oxidative conversion of Δ5-3-hydroxy steroids to a Δ4-3-oxo configuration. This conversion is carried out in two separate, sequential reactions; in the first reaction, which requires NAD+, the enzyme catalyses the dehydrogenation of the 3β-hydroxy steroid to a 3-oxo intermediate. In the second reaction the reduced cosubstrate, which remains attached to the enzyme, activates the isomerization of the Δ5 form to a Δ4 form (cf. EC 5.3.3.1, steroid Δ-isomerase). Substrates include dehydroepiandrosterone (which is converted into androst-5-ene-3,17-dione), pregnenolone (converted to progesterone) and cholest-5-en-3-one, an intermediate of cholesterol degradation. |
| Links to other databases: |
BRENDA, EXPASY, Gene, KEGG, MetaCyc, PDB, CAS registry number: 9044-85-3 |
| References: |
| 1. |
Cheatum, S.G. and Warren, J.C. Purification and properties of 3-β-hydroxysteroid dehydrogenase and Δ-5-3-ketosteroid isomerase from bovine corpora lutea. Biochim. Biophys. Acta 122 (1966) 1–13. [PMID: 4226148] |
| 2. |
Koritz, S.B. The conversion of prepnenolone to progesterone by small particle from rat adrenal. Biochemistry 3 (1964) 1098–1102. [PMID: 14220672] |
| 3. |
Neville, A.M., Orr, J.C. and Engel, L.L. Δ5-3β-Hydroxy steroid dehydrogenase activities of bovine adrenal cortex. Biochem. J. 107 (1968) 20. |
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| [EC 1.1.1.145 created 1972] |
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