Cytochrome b5 reductase

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cytochrome-b5 reductase
Ribbon diagram of erythrocytic methemoglobin reductase with FAD bound. From PDB: 1UMK​.
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EC no.1.6.2.2
CAS no.9032-25-1
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Cytochrome b5 reductase
Identifiers
SymbolCYB5R
InterProIPR001834
Membranome421

Cytochrome-b5 reductase is a NADH-dependent enzyme that converts ferricytochrome from a Fe3+ form to a Fe2+ form.[1] 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.[citation needed]

The following four human genes encode cytochrome-b5 reductases:[citation needed]

See also

References

  1. ^ Tamura M, Yubisui T, Takeshita M, Kawabata S, Miyata T, Iwanaga S (May 1987). "Structural comparison of bovine erythrocyte, brain, and liver NADH-cytochrome b5 reductase by HPLC mapping". Journal of Biochemistry. 101 (5): 1147–59. doi:10.1093/oxfordjournals.jbchem.a121979. PMID 3654589.

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