ENZYME entry: EC 1.14.18.9

Accepted Name

4alpha-methylsterol monooxygenase

Alternative Name(s)

4-methylsterol oxidase

methylsterol hydroxylase

methylsterol monooxygenase

Reaction catalysed

4,4-dimethyl-5alpha-cholest-7-en-3beta-ol + 6 Fe(II)-[cytochrome b5] + 5 H(+) + 3 O2 = 4alpha-carboxy-4beta-methyl-5alpha-cholest-7-ene-3beta-ol + 6 Fe(III)-[cytochrome b5] + 4 H2O

Comment(s)

This enzyme is found in fungi and animals and catalyzes a step in the biosynthesis of important sterol molecules such as ergosterol and cholesterol, respectively.
The enzyme acts on the 4alpha-methyl group.
Subsequent decarboxylation by EC 1.1.1.170 occurs concomitantly with epimerization of the remaining 4beta-methyl into the 4alpha position, thus making it a suitable substrate for a second round of catalysis. cf. EC 1.14.13.246, EC 1.14.18.10 and EC 1.14.18.11.
Formerly EC 1.14.13.72 and EC 1.14.99.16.

Cross-references

BRENDA

1.14.18.9

EC2PDB

1.14.18.9

ExplorEnz

1.14.18.9

PRIAM enzyme-specific profiles

1.14.18.9

KEGG Ligand Database for Enzyme Nomenclature

1.14.18.9

IUBMB Enzyme Nomenclature

1.14.18.9

IntEnz

1.14.18.9

MEDLINE

Find literature relating to 1.14.18.9

MetaCyc

1.14.18.9

Rhea expert-curated reactions

1.14.18.9

UniProtKB/Swiss-Prot

O59933, ERG25_CANAL	Q5ZLL6, MSMO1_CHICK	Q7ZW77, MSMO1_DANRE
Q15800, MSMO1_HUMAN	Q4R4Q4, MSMO1_MACFA	Q9CRA4, MSMO1_MOUSE
Q6UGB2, MSMO1_PIG	Q5R574, MSMO1_PONAB	O35532, MSMO1_RAT
Q55D52, MSMOA_DICDI	Q55D54, MSMOB_DICDI	Q8L7W5, SMO11_ARATH
Q1EC69, SMO12_ARATH	F4JLZ6, SMO13_ARATH	Q9ZW22, SMO21_ARATH
Q8VWZ8, SMO22_ARATH

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