Reaction: 5α-cholest-7-en-3β-ol + NAD(P)H + H+ + O2 = cholesta-5,7-dien-3β-ol + NAD(P)+ + 2 H2O
For diagram click here.
Glossary: lathosterol = 5α-cholest-7-en-3β-ol
7-dehydrocholesterol = cholesta-5,7-dien-3β-ol
Other name(s): Δ7-sterol Δ5-dehydrogenase; Δ7-sterol 5-desaturase; Δ7-sterol-C5(6)-desaturase; 5-DES
Systematic name: 5α-cholest-7-en-3β-ol, NAD(P)H:oxygen 5-oxidoreductase
Comments: This enzyme catalyses the introduction of a C5 double bond into the B ring of Δ7-sterols to yield the corresponding Δ5,7-sterols in mammals, yeast and plants [4]. Forms part of the plant sterol biosynthesis pathway.
Links to other databases: BRENDA, EXPASY, KEGG, CAS registry number: 37255-37-1
References:
1. Dempsey, M.E., Seaton, J.D., Schroepfer, G.J. and Trockman, R.W. The intermediary role of Δ5,7-cholestadien-3β-ol in cholesterol biosynthesis. J. Biol. Chem. 239 (1964) 1381-1387. [PMID: 14189869]
2. Nishino, H., Nakaya, J., Nishi, S., Kurosawa, T. and Ishibashi, T. Temperature-induced differential kinetic properties between an initial burst and the following steady state in membrane-bound enzymes: studies on lathosterol 5-desaturase. Arch. Biochem. Biophys. 339 (1997) 298-304. [PMID: 9056262]
3. Taton, M. and Rahier, A. Plant sterol biosynthesis: identification and characterization of higher plant Δ7-sterol C5(6)-desaturase. Arch. Biochem. Biophys. 325 (1996) 279-288. [PMID: 8561508]
4. Taton, M., Husselstein, T., Benveniste, P. and Rahier, A. Role of highly conserved residues in the reaction catalyzed by recombinant Δ7-sterol-C5(6)-desaturase studied by site-directed mutagenesis. Biochemistry 39 (2000) 701-711. [PMID: 10651635]