Δ7-sterol 5(6)-desaturase
| Δ7-sterol 5(6)-desaturase | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Identifiers | |||||||||
| EC no. | 1.14.19.20 | ||||||||
| CAS no. | 37255-37-1 | ||||||||
| Databases | |||||||||
| IntEnz | IntEnz view | ||||||||
| BRENDA | BRENDA entry | ||||||||
| ExPASy | NiceZyme view | ||||||||
| KEGG | KEGG entry | ||||||||
| MetaCyc | metabolic pathway | ||||||||
| PRIAM | profile | ||||||||
| PDB structures | RCSB PDB PDBe PDBsum | ||||||||
| |||||||||
In enzymology, a Δ7-sterol 5(6)-desaturase (EC 1.14.19.20) is an enzyme that catalyzes the chemical reaction
Δ7-sterol + 2 ferrocytochrome b5 + O2 + 2 H+ = Δ5,7-sterol + 2 ferricytochrome b5 + 2 H2O
Function
This enzyme participates in biosynthesis of steroids; in vertebrates the pathway leads to cholesterol.[1][2][3] The oxidation reaction which it catalyses is:
It uses two molecules of the cofactor ferrocytochrome b5 with two protons and one oxygen to convert lathosterol to 7-dehydrocholesterol and water. In plants it acts on episterol.[1][4][5]
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 oxidation of a pair of donors resulting in the reduction of molecular oxygen to two molecules of water.
Nomenclature
The systematic name of this enzyme class is Δ7-sterol,ferrocytochrome b5:oxygen oxidoreductase 5,6-dehydrogenating. Other names in common use include:
- lathosterol oxidase
- Δ7-sterol Δ5-dehydrogenase
- Δ7-sterol 5-desaturase
- Δ7-sterol-C5(6)-desaturase
- 5-DES
Gene names:
See also
References
- ^ a b Enzyme 1.14.19.20 at KEGG Pathway Database.
- ^ Dempsey ME, Seaton JD, Schroepfer GJ, Trockman RW (1964). "The Intermediary Role of Δ5,7-cholestadien-3-β-ol in Cholesterol Biosynthesis". J. Biol. Chem. 239: 1381–7. doi:10.1016/S0021-9258(18)91325-6. 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.