ENZYME entry: EC 126.96.36.199
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|Sterol 4-alpha-carboxylic decarboxylase.|
|Sterol-4-alpha-carboxylate 3-dehydrogenase (decarboxylating).|
|A 3-beta-hydroxysteroid-4-alpha-carboxylate + NAD(P)(+) <=> a 3-oxosteroid + CO(2) + NAD(P)H|
- The enzyme participates in the biosynthesis of several important
sterols such as ergosterol and cholesterol.
- It is part of a three enzyme system that removes methyl groups from
the C-4 position of steroid molecules.
- The first enzyme, EC 188.8.131.52, catalyzes three successive oxidations
of the methyl group, resulting in a carboxyl group; the second
enzyme, EC 184.108.40.206, catalyzes an oxidative decarboxylation that
results in a reduction of the 3-beta-hydroxy group at the C-3 carbon
to an oxo group; and the last enzyme, EC 220.127.116.110, reduces the 3-oxo
group back to a 3-beta-hydroxyl.
- If a second methyl group remains at the C-4 position, this enzyme
also catalyzes its epimerization from 4-beta to 4-alpha orientation,
so it could serve as a substrate for a second round of demethylation.
- Cf. EC 18.104.22.1688.
|PRIAM enzyme-specific profiles||22.214.171.124|
|KEGG Ligand Database for Enzyme Nomenclature||126.96.36.199|
|IUBMB Enzyme Nomenclature||188.8.131.52|
|MEDLINE||Find literature relating to 184.108.40.206|
|O43050, ERG26_SCHPO; ||P53199, ERG26_YEAST; ||Q9FX01, HSDD1_ARATH; |
|Q67ZE1, HSDD2_ARATH; ||A9X4U2, HSDD3_ARATH; ||Q3ZBE9, NSDHL_BOVIN; |
|Q54L85, NSDHL_DICDI; ||Q15738, NSDHL_HUMAN; ||Q9R1J0, NSDHL_MOUSE; |
|Q5PPL3, NSDHL_RAT; |
entries corresponding to 1.1.1.-
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