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3β-hydroxysteroid Dehydrogenase

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Title: 3β-hydroxysteroid Dehydrogenase  
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Subject: Dihydrotestosterone, Congenital adrenal hyperplasia due to 3 beta-hydroxysteroid dehydrogenase deficiency, Trilostane, Epiandrosterone
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3β-hydroxysteroid Dehydrogenase

3β-hydroxysteroid dehydrogenase/Δ-5-4 isomerase
EC number CAS number IntEnz BRENDA ExPASy KEGG MetaCyc metabolic pathway
PRIAM PDB structures PDBsum
Gene Ontology EGO
hydroxy-Δ-5-steroid dehydrogenase,
3β- and steroid Δ-isomerase 1
Symbol HSD3B1
Alt. symbols HSDB3, HSD3B
Entrez HUGO OMIM RefSeq UniProt EC number Locus p13-p11
hydroxy-Δ-5-steroid dehydrogenase,
3β- and steroid Δ-isomerase 2
Symbol HSD3B2
Entrez HUGO OMIM RefSeq UniProt EC number Locus p13.1

3-β-HSD (or 3-β-hydroxysteroid dehydrogenase/Δ-5-4 isomerase) (HSD3B2 genes.

It is also known as delta 5-delta 4-isomerase, which catalyzes the oxidative conversion of delta 5-3 beta- hydroxysteroids to the delta 4-3-keto configuration and is, therefore, essential for the biosynthesis of all classes of hormonal steroids, namely progesterone, glucocorticoids, mineralocorticoids, androgens, and estrogens.[2] The 3-beta HSD complex is responsible for the conversion of:


3-β-HSD belongs to the family of oxidoreductases, to be specific, those acting on the CH-OH group of donor with NAD+ or NADP+ as acceptor. This enzyme participates in c21-steroid hormone metabolism and androgen and estrogen metabolism.

3-β-HSD catalyzes the chemical reaction:

a 3β-hydroxy-Δ5-steroid + NAD+ \rightleftharpoons a 3-oxo-Δ5-steroid + NADH + H+

Thus, the two substrates of this enzyme are 3β-hydroxy-Δ5-steroid and NAD+, whereas its 3 products are 3-oxo-Δ5-steroid, NADH, and H+.


Humans express two 3-β-HSD isozymes, HSD3B1 (type I) and HSD3B2 (type II).[3] The type I isoenzyme is expressed in placenta and peripheral tissues, whereas the type II 3β-HSD isoenzyme is expressed in the adrenal gland, ovary, and testis.


The systematic name of this enzyme class is 3β-hydroxy-Δ5-steroid:NAD+ 3-oxidoreductase. Other names in common use include:

  • 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-3β-hydroxysteroid dehydrogenase
  • 3β-hydroxy-5-ene-steroid dehydrogenase


3-β-HSD is inhibited by trilostane.[4]

Biosynthetic pathway

Clinical significance

A deficiency in the type II form through mutations in HSD3B2 is responsible for a rare form of congenital adrenal hyperplasia.[5] No human condition has yet been linked to a deficiency in the type I enzyme. Its importance in placental progesterone production expression suggests that such a mutation would be embryonically lethal.

See also

  • 3α-Hydroxysteroid dehydrogenase (3α-HSD)


Further reading

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