Sterol 14-demethylase
| sterol 14alpha-demethylase | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Identifiers | |||||||||
| EC no. | 1.14.14.154 | ||||||||
| Databases | |||||||||
| BRENDA | enzyme data | ||||||||
| ExPASy | NiceZyme view | ||||||||
| KEGG | enzyme entry | ||||||||
| MetaCyc | metabolic pathway | ||||||||
| Rhea | reactions | ||||||||
| PDB structures | RCSB PDB PDBe PDBsum | ||||||||
| Gene Ontology | AmiGO / QuickGO | ||||||||
| |||||||||
In enzymology, a sterol 14α-demethylase (EC 1.14.14.154, formerly 1.14.13.70) or CYP51 is an enzyme of the cytochrome P450 (CYP) superfamily. It is an important enzyme in the sterol biosynthesis, responsible for removing a methyl group from lanosterol (in animals and fungi) or obtusifoliol (in plants).
It catalyzes a chemical reaction generally described as:
- a 14alpha-methyl steroid + 3 reduced [NADPH–hemoprotein reductase] + 3 O2 = a Delta(14) steroid + formate + 3 oxidized [NADPH–hemoprotein reductase] + 4 H2O + 4 H(+)
A particular example is:
- obtusifoliol + 3 O2 + 3 NADPH + 3 H+ 4alpha-methyl-5alpha-ergosta-8,14,24(28)-trien-3beta-ol + formate + 3 NADP+ + 4 H2O
The 4 substrates here are obtusifoliol, O2, NADPH, and H+, whereas its 4 products are 4alpha-methyl-5alpha-ergosta-8,14,24(28)-trien-3beta-ol, formate, NADP+, and H2O. This enzyme 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 incorporation of one atom of oxygen into the other donor.
The 14α-demethylase (CYP51) is present in some bacteria, animals, fungi, plants, and some protozoa: the only "ubiquitous P450". It appears in every sterol biosynthesis pathway known as of 2007. In animals (including humans), CYP51A1 catalyzes the demethylation of lanosterol or 24,25-dihydrolanosterol to create an important precursor that is eventually converted into cholesterol, a key determinant of the permeability and rigidity of plasma membranes. In fungi, the same reaction leads to the production of ergosterol, which plays an analogous role. The differences between animal and fungal versions of this enzyme allow antifungal medications to inhibit the fungal version and prevent the production of this key compound.