| cytochrome-b5 reductase | |||||||||
|---|---|---|---|---|---|---|---|---|---|
) | |||||||||
| Identifiers | |||||||||
| EC number | 1.6.2.2 | ||||||||
| CAS number | 9032-25-1 | ||||||||
| Databases | |||||||||
| IntEnz | IntEnz view | ||||||||
| BRENDA | BRENDA entry | ||||||||
| ExPASy | NiceZyme view | ||||||||
| KEGG | KEGG entry | ||||||||
| MetaCyc | metabolic pathway | ||||||||
| PRIAM | profile | ||||||||
| PDB structures | RCSB PDB PDBe PDBsum | ||||||||
| Gene Ontology | AmiGO / QuickGO | ||||||||
| |||||||||
| Cytochrome b5 reductase | |
|---|---|
| Identifiers | |
| Symbol | CYB5R |
| InterPro | IPR001834 |
| Membranome | 421 |
Cytochrome-b5 reductase is a NADH-dependent enzyme that converts ferricytochrome from a Fe3+ form to a Fe2+ form. It contains FAD and catalyzes the reaction:
NADH + H+ + 2 ferricytochrome b5 = NAD+ + 2 ferrocytochrome b5
In its b5-reducing capacity, this enzyme is involved in desaturation and elongation of fatty acids, cholesterol biosynthesis, and drug metabolism.
This enzyme can also reduce methemoglobin to normal hemoglobin, gaining it the inaccurate synonym methemoglobin reductase. Isoforms expressed in erythrocytes (CYB5R1, CYB5R3) perform this function in vivo. Ferricyanide is another substrate in vitro.
The following four human genes encode cytochrome-b5 reductases:
- CYB5R1
- CYB5R2
- CYB5R3
- CYB5R4
See also
- Cytochrome b5
- Diaphorase
- Methemoglobinemia
- Reductase
- Leghemoglobin reductase
External links
- Cytochrome-B(5)+Reductase at the US National Library of Medicine Medical Subject Headings (MeSH)