20alpha-hydroxysteroid dehydrogenase
| 20-α-hydroxysteroid dehydrogenase | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Identifiers | |||||||||
| EC number | 1.1.1.149 | ||||||||
| CAS number | Template:CAS | ||||||||
| Databases | |||||||||
| IntEnz | IntEnz view | ||||||||
| BRENDA | BRENDA entry | ||||||||
| ExPASy | NiceZyme view | ||||||||
| KEGG | KEGG entry | ||||||||
| MetaCyc | metabolic pathway | ||||||||
| PRIAM | profile | ||||||||
| PDB structures | RCSB PDB PDBe PDBsum | ||||||||
| Gene Ontology | AmiGO / EGO | ||||||||
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In enzymology, a 20-α-hydroxysteroid dehydrogenase (EC 1.1.1.149) is an enzyme that catalyzes the chemical reaction
- 17alpha,20alpha-dihydroxypregn-4-en-3-one + NAD(P)+
17alpha-hydroxyprogesterone + NAD(P)H + H+
The 3 substrates of this enzyme are 17alpha,20alpha-dihydroxypregn-4-en-3-one, NAD+, and NADP+, whereas its 4 products are 17-alpha-hydroxyprogesterone, NADH, NADPH, and H+.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is 20alpha-hydroxysteroid:NAD(P)+ 20-oxidoreductase. Other names in common use include 20alpha-hydroxy steroid dehydrogenase, 20alpha-hydroxy steroid dehydrogenase, 20alpha-HSD, and 20alpha-HSDH. This enzyme participates in c21-steroid hormone metabolism.
20alpha-HSD has been initially described as a progesterone metabolizing enzyme of the ovary. On a functional level, ovarian 20alpha-HSD is actively involved in the control of progesterone homeostasis in pregnancy of rats and mice. While 20alpha-HSD expression and activity is downregulated in the corpus luteum of pregnancy, 24 hrs prior to parturition ovarian 20alpha-HSD activity is acutely stimulated. Accordingly, in mice with targeted deletion of the 20alpha-HSD gene, progesterone blood concentration remain high throughout pregnancy which results in a delay of 2–4 days in parturition. Indicating that expression of 20alpha-HSD activity is mandatory for the induction of parturition through reduction of progesterone blood concentration. In mice, 20alpha-HSD is also expressed in the adrenals, kidneys, brain, thymus, T cells and bone marrow. Its induction in hematopoietic cells was used as an assay for the identification of T cell derived factor interleukin-3. In addition, the enzyme reduces and inactivates 17-deoxycorticosterone, the precursor of aldosterone and corticosterone.
Structural studies
As of late 2007, 3 structures have been solved for this class of enzymes, with PDB accession codes 1MRQ, 1Q13, and 1Q5M.
See also
References
Further reading
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