Methylsterol monooxygenase

Methylsterol monooxygenase
Identifiers
EC number 1.14.13.72
CAS number 37256-80-7
Databases
IntEnz IntEnz view
BRENDA BRENDA entry
ExPASy NiceZyme view
KEGG KEGG entry
MetaCyc metabolic pathway
PRIAM profile
PDB structures RCSB PDB PDBe PDBsum

Methylsterol monooxygenase (EC 1.14.13.72, 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).[1][2][3][4][5][6][7] This enzyme catalyses the following chemical reaction

4,4-dimethyl-5alpha-cholest-7-en-3beta-ol + 3 NAD(P)H + 3 H+ + 3 O2 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 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 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 3beta-hydroxy-4beta-methyl-5alpha-cholest-7-ene-4alpha-carboxylate + NAD(P)+ + H2O

Methylsterol monooxygenase requires cytochrome b5.

References

  1. Rahier, A.; Smith, M.; Taton, M. (1997). "The role of cytochrome b5 in 4α-methyl-oxidation and C5(6) desaturation of plant sterol precursors". Biochem. Biophys. Res. Commun. 236 (2): 434–437. doi:10.1006/bbrc.1997.6974. PMID 9240456.
  2. Pascal, S.; Taton, M.; Rahier, A. (1993). "Plant sterol biosynthesis. Identification and characterization of two distinct microsomal oxidative enzymatic systems involved in sterol C4-demethylation". J. Biol. Chem. 268 (16): 11639–11654. PMID 8505296.
  3. Kawata, S.; Trzaskos, J.M.; Gaylor, J.L. (1986). "Affinity chromatography of microsomal enzymes on immobilized detergent-solubilized cytochrome b5". J. Biol. Chem. 261 (8): 3790–3799. PMID 3949790.
  4. Fukushima, H.; Grinstead, G.F.; Gaylor, J.L. (1981). "Total enzymic synthesis of cholesterol from lanosterol. Cytochrome b5-dependence of 4-methyl sterol oxidase". J. Biol. Chem. 256 (10): 4822–4826. PMID 7228857.
  5. Brady, D.R.; Crowder, R.D.; Hayes, W.J. (1980). "Mixed function oxidases in sterol metabolism. Source of reducing equivalents". J. Biol. Chem. 255 (22): 10624–10629. PMID 7430141.
  6. Gaylor, J.L.; Mason, H.S. (1968). "Investigation of the component reactions of oxidative sterol demethylation. Evidence against participation of cytochrome P-450". J. Biol. Chem. 243 (19): 4966–4972. PMID 4234469.
  7. Miller, W.L.; Kalafer, M.E.; Gaylor, J.L.; Delwicke, C.V. (1967). "Investigation of the component reactions of oxidative sterol demethylation. Study of the aerobic and anaerobic processes". Biochemistry. 6 (9): 2673–2678. doi:10.1021/bi00861a005. PMID 4383278.
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