Δ7-sterol 5(6)-desaturase
Enzyme
From Wikipedia, the free encyclopedia
In enzymology, a Δ7-sterol 5(6)-desaturase (EC 1.14.19.20) is an enzyme that catalyzes the chemical reaction
| Δ7-sterol 5(6)-desaturase | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Identifiers | |||||||||
| EC no. | 1.14.19.20 | ||||||||
| CAS no. | 37255-37-1 | ||||||||
| Databases | |||||||||
| BRENDA | enzyme data | ||||||||
| ExPASy | NiceZyme view | ||||||||
| KEGG | enzyme entry | ||||||||
| MetaCyc | metabolic pathway | ||||||||
| Rhea | reactions | ||||||||
| PDB structures | RCSB PDB PDBe PDBsum | ||||||||
| |||||||||
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:
