Lathosterol oxidase

In enzymology, a lathosterol oxidase (EC 1.14.21.6) is an enzyme that catalyzes the chemical reaction

5α-cholest-7-en-3β-ol + NAD(P)H + H⁺ + O₂ ${\displaystyle \rightleftharpoons }$ cholesta-5,7-dien-3β-ol + NAD(P)+ + 2 H₂O

The five substrates of this enzyme are 5α-cholest-7-en-3β-ol, NADH, NADPH, H⁺, and O₂. Its four products are cholesta-5,7-dien-3β-ol (provitamin D₃), NAD⁺, NADP⁺, and H₂O.

Classification[]

This enzyme is one of C-5 sterol desaturases, belongs to the family of oxidoreductases, specifically those acting on paired donors, with O₂ as oxidant and incorporation or reduction of oxygen. The oxygen incorporated need not be derived from O₂ with NADH or NADPH as one donor, and the other dehydrogenated.

Nomenclature[]

The systematic name of this enzyme class is 5α-cholest-7-en-3β-ol,NAD(P)H:oxygen 5-oxidoreductase. Other names in common use include Δ⁷-sterol Δ⁵-dehydrogenase, Δ⁷-sterol 5-desaturase, Δ⁷-sterol-C5(6)-desaturase, and 5-DES.

Biological role[]

This enzyme participates in biosynthesis of steroids. It has two cofactors: FAD, and FMN.

See also[]

• Fatty acid desaturase
• C-5 sterol desaturase

References[]

• Dempsey ME, Seaton JD, Schroepfer GJ, Trockman RW (1964). "The Intermediary Role of Δ^5,7-cholestadien-3-β-ol in Cholesterol Biosynthesis". J. Biol. Chem. 239: 1381–7. PMID 14189869.
• Nishino H, Nakaya J, Nishi S, Kurosawa T, Ishibashi T (1997). "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 (2): 298–304. doi:10.1006/abbi.1996.9871. PMID 9056262.
• Taton M, Rahier A (1996). "Plant sterol biosynthesis: identification and characterization of higher plant Δ⁷-sterol C5(6)-desaturase". Arch. Biochem. Biophys. 325 (2): 279–88. doi:10.1006/abbi.1996.0035. PMID 8561508.
• Taton M, Husselstein T, Benveniste P, Rahier A (2000). "Role of highly conserved residues in the reaction catalyzed by recombinant Δ⁷-sterol-C5(6)-desaturase studied by site-directed mutagenesis". Biochemistry. 39 (4): 701–11. doi:10.1021/bi991467t. PMID 10651635.