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ENZYME entry: EC 1.1.1.170
Accepted Name |
3beta-hydroxysteroid-4alpha-carboxylate 3-dehydrogenase
(decarboxylating).
|
Alternative Name(s) |
3beta-hydroxy-4alpha-methylcholestenecarboxylate 3-dehydrogenase
(decarboxylating). |
3beta-hydroxy-4beta-methylcholestenecarboxylate 3-dehydrogenase
(decarboxylating). |
3beta-hydroxy-4beta-methylcholestenoate dehydrogenase. |
sterol-4alpha-carboxylate 3-dehydrogenase (decarboxylating). |
sterol 4alpha-carboxylic decarboxylase. |
Reaction catalysed |
- a 3beta-hydroxysteroid-4alpha-carboxylate + NADP(+) <=> a 3-oxosteroid + CO2 + NADPH
- a 3beta-hydroxysteroid-4alpha-carboxylate + NAD(+) <=> a 3-oxosteroid + CO2 + NADH
|
Comment(s) |
- 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 1.14.18.9, catalyzes three successive oxidations
of the methyl group, resulting in a carboxyl group; the second
enzyme, EC 1.1.1.170, catalyzes an oxidative decarboxylation that
results in a reduction of the 3beta-hydroxy group at the C-3 carbon
to an oxo group; and the last enzyme, EC 1.1.1.270, reduces the 3-oxo
group back to a 3beta-hydroxyl.
- If a second methyl group remains at the C-4 position, this enzyme
also catalyzes its epimerization from 4beta to 4alpha orientation,
so it could serve as a substrate for a second round of demethylation.
- Cf. EC 1.1.1.418.
|
Cross-references |
BRENDA | 1.1.1.170 |
EC2PDB | 1.1.1.170 |
ExplorEnz | 1.1.1.170 |
PRIAM enzyme-specific profiles | 1.1.1.170 |
KEGG Ligand Database for Enzyme Nomenclature | 1.1.1.170 |
IUBMB Enzyme Nomenclature | 1.1.1.170 |
IntEnz | 1.1.1.170 |
MEDLINE | Find literature relating to 1.1.1.170 |
MetaCyc | 1.1.1.170 |
Rhea expert-curated reactions | 1.1.1.170 |
UniProtKB/Swiss-Prot |
|
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