Methylsterol monooxygenase

Methylsterol monooxygenase (, methylsterol hydroxylase, 4-methylsterol oxidase, 4,4-dimethyl-5alpha-cholest-7-en-3beta-ol,hydrogen-donor:oxygen oxidoreductase (hydroxylating)) is an enzyme with systematic name 4,4-dimethyl-5alpha-cholest-7-en-3beta-ol,NAD(P)H:oxygen oxidoreductase (hydroxylating). This enzyme catalyses the following chemical reaction


 * 4,4-dimethyl-5alpha-cholest-7-en-3beta-ol + 3 NAD(P)H + 3 H+ + 3 O2 $$\rightleftharpoons$$ 3beta-hydroxy-4beta-methyl-5alpha-cholest-7-ene-4alpha-carboxylate + 3 NAD(P)+ + 4 H2O (overall reaction)
 * (1a) 4,4-dimethyl-5alpha-cholest-7-en-3beta-ol + NAD(P)H + H+ + O2 $$\rightleftharpoons$$ 4beta-hydroxymethyl-4alpha-methyl-5alpha-cholest-7-en-3beta-ol + NAD(P)+ + H2O
 * (1b) 4beta-hydroxymethyl-4alpha-methyl-5alpha-cholest-7-en-3beta-ol + NAD(P)H + H+ + O2 $$\rightleftharpoons$$ 3beta-hydroxy-4beta-methyl-5alpha-cholest-7-ene-4alpha-carbaldehyde + NAD(P)+ + 2 H2O
 * (1c) 3beta-hydroxy-4beta-methyl-5alpha-cholest-7-ene-4alpha-carbaldehyde + NAD(P)H + H+ + O2 $$\rightleftharpoons$$ 3beta-hydroxy-4beta-methyl-5alpha-cholest-7-ene-4alpha-carboxylate + NAD(P)+ + H2O

Methylsterol monooxygenase requires cytochrome b5.