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EC 1.1.1.145 Details
EC number
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+
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
CAS registry number
9044-85-3
Comment
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 coenzyme, 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.
History
created 1972
EC Tree
1.1.1.68 created 1965, deleted 1978 [transferred to EC 1.1.99.15, deleted 1980]
1.1.1.70 created 1965, deleted 1978
1.1.1.74 created 1972, deleted 1976
1.1.1.89 created 1972, deleted 1976
1.1.1.109 created 1972, deleted 1976
1.1.1.139 created 1972, deleted 1978
1.1.1.155 created 1976, deleted 2004
1.1.1.171 created 1978, deleted 1984
1.1.1.180 created 1983, deleted 1984
1.1.1.182 created 1983, deleted 1990
1.1.1.204 created 1972 as EC 1.2.1.37, transferred 1984 to EC 1.1.1.204, modified 1989, deleted 2004
1.1.1.242 created 1992, deleted 2001
1.1.1.249 provisional version created 1999, deleted 1999 (reinstated 2001 as EC 2.5.1.46)
1.1.1.253 created 1999, deleted 2003