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Your query returned 1 entry. Printable version
EC | 1.14.18.10 | ||||||||
Accepted name: | plant 4,4-dimethylsterol C-4α-methyl-monooxygenase | ||||||||
Reaction: | 24-methylidenecycloartanol + 6 ferrocytochrome b5 + 3 O2 + 6 H+ = 3β-hydroxy-4β,14α-dimethyl-9β,19-cyclo-5α-ergost-24(241)-en-4α-carboxylate + 6 ferricytochrome b5 + 4 H2O (overall reaction) (1a) 24-methylidenecycloartanol + 2 ferrocytochrome b5 + O2 + 2 H+ = 4α-(hydroxymethyl)-4β,14α-dimethyl-9β,19-cyclo-5α-ergost-24(241)-en-3β-ol + 2 ferricytochrome b5 + H2O (1b) 4α-(hydroxymethyl)-4β,14α-dimethyl-9β,19-cyclo-5α-ergost-24(241)-en-3β-ol + 2 ferrocytochrome b5 + O2 + 2 H+ = 4α-formyl-4β,14α-dimethyl-9β,19-cyclo-5α-ergost-24(241)-en-3β-ol + 2 ferricytochrome b5 + 2 H2O (1c) 4α-formyl-4β,14α-dimethyl-9β,19-cyclo-5α-ergost-24(241)-en-3β-ol + 2 ferrocytochrome b5 + O2 + 2 H+ = 3β-hydroxy-4β,14α-dimethyl-9β,19-cyclo-5α-ergost-24(241)-en-4α-carboxylate + 2 ferricytochrome b5 + H2O |
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Glossary: | 24-methylidenecycloartanol = 4α,4β,14α-trimethyl-9β,19-cyclo-5α-ergost-24(241)-en-3β-ol | ||||||||
Other name(s): | SMO1 (gene name) | ||||||||
Systematic name: | 24-methylidenecycloartanol,ferrocytochrome-b5:oxygen oxidoreductase (C-4α-methyl-hydroxylating) | ||||||||
Comments: | This plant enzyme catalyses a step in the biosynthesis of sterols. It acts on the 4α-methyl group of the 4,4-dimethylated intermediate 24-methylidenecycloartanol and catalyses three successive oxidations, turning it into a carboxyl group. The carboxylate is subsequently removed by EC 1.1.1.418, plant 3β-hydroxysteroid-4α-carboxylate 3-dehydrogenase (decarboxylating), which also catalyses the epimerization of the remaining 4β-methyl into the 4α position. Unlike the fungal/animal enzyme EC 1.14.18.9, 4α-methylsterol monooxygenase, this enzyme is not able to remove the methyl group from C-4-monomethylated substrates. That activity is performed in plants by a second enzyme, EC 1.14.18.11, plant 4α-monomethylsterol monooxygenase. | ||||||||
Links to other databases: | BRENDA, EXPASY, KEGG, MetaCyc | ||||||||
References: |
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