Information on EC - 3beta-hydroxy-DELTA5-steroid dehydrogenase

for references in articles please use BRENDA:EC1.1.1.145
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IUBMB Comments
This activity is found in several bifunctional enzymes that catalyse the oxidative conversion of Delta5-3-hydroxy steroids to a Delta4-3-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 3beta-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 Delta5 form to a Delta4 form (cf. EC, steroid Delta-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.
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The enzyme appears in viruses and cellular organisms
3-beta-hydroxy-5-ene steroid dehydrogenase, 3-beta-hydroxy-delta(5)-steroid dehydrogenase, 3-beta-hydroxysteroid dehydrogenase, 3-beta-hydroxysteroid dehydrogenase type-2, 3beta hydroxysteroid dehydrogenase, 3beta-HSD, 3beta-HSD type II, 3beta-HSD1, 3beta-HSD2, 3beta-HSD22, more
a 3beta-hydroxy-DELTA5-steroid + NAD+ = a 3-oxo-DELTA5-steroid + NADH + H+
show the reaction diagram