ExplorEnz: EC 1.6.2.4

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1.6.2.4

Accepted name:

NADPH—hemoprotein reductase

Reaction:

NADPH + H⁺ + n oxidized hemoprotein = NADP⁺ + n reduced hemoprotein

Other name(s):

CPR; FAD-cytochrome c reductase; NADP-cytochrome c reductase; NADP-cytochrome reductase; NADPH-dependent cytochrome c reductase; NADPH:P-450 reductase; NADPH:ferrihemoprotein oxidoreductase; NADPH—cytochrome P-450 oxidoreductase; NADPH-cytochrome c oxidoreductase; NADPH-cytochrome c reductase; NADPH—cytochrome p-450 reductase; NADPH-ferricytochrome c oxidoreductase; NADPH-ferrihemoprotein reductase; TPNH₂ cytochrome c reductase; TPNH-cytochrome c reductase; aldehyde reductase (NADPH-dependent); cytochrome P-450 reductase; cytochrome c reductase (reduced nicotinamide adenine dinucleotide phosphate, NADPH, NADPH-dependent); dihydroxynicotinamide adenine dinucleotide phosphate-cytochrome c reductase; ferrihemoprotein P-450 reductase; reduced nicotinamide adenine dinucleotide phosphate-cytochrome c reductase; reductase, cytochrome c (reduced nicotinamide adenine dinucleotide phosphate)

Systematic name:

NADPH:hemoprotein oxidoreductase

Comments:

A flavoprotein containing both FMN and FAD. This enzyme catalyses the transfer of electrons from NADPH, an obligatory two-electron donor, to microsomal P-450 monooxygenases (e.g. EC 1.14.14.1, unspecific monooxygenase) by stabilizing the one-electron reduced form of the flavin cofactors FAD and FMN. It also reduces cytochrome b₅ and cytochrome c. The number n in the equation is 1 if the hemoprotein undergoes a 2-electron reduction, and is 2 if it undergoes a 1-electron reduction.

Links to other databases:

BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 9023-03-4

References:

1.	Haas, E., Horecker, B.L. and Hogness, T.R. The enzymatic reduction of cytochrome c, cytochrome c reductase. J. Biol. Chem. 136 (1940) 747–774.
2.	Horecker, B.L. Triphosphopyridine nucleotide-cytochrome c reductase in liver. J. Biol. Chem. 183 (1950) 593–605.
3.	Lu, A.Y.H., Junk, K.W. and Coon, M.J. Resolution of the cytochrome P-450-containing ω-hydroxylation system of liver microsomes into three components. J. Biol. Chem. 244 (1969) 3714–3721. [PMID: 4389465]
4.	Masters, B.S.S., Kamin, H., Gibson, Q.H. and Williams, C.H., Jr. Studies on the mechanism of microsomal triphosphopyridine nucleotide-cytochrome c reductase. J. Biol. Chem. 240 (1965) 921–931. [PMID: 14275154]
5.	Williams, C.H., Jr. and Kamin, H. Microsomal triphosphopyridine nucleotide-cytochrome c reductase in liver. J. Biol. Chem. 237 (1962) 587–595. [PMID: 14007123]
6.	Masters, B.S.S., Bilimoria, M.H, Kamen, H. and Gibson, Q.H. The mechanism of 1- and 2-electron transfers catalyzed by reduced triphosphopyridine nucleotide-cytochrome c reductase. J. Biol. Chem. 240 (1965) 4081–4088. [PMID: 4378860]
7.	Sevrioukova, I.F. and Peterson, J.A. NADPH-P-450 reductase: Structural and functional comparisons of the eukaryotic and prokaryotic isoforms. Biochimie 77 (1995) 562–572. [DOI] [PMID: 8589067]
8.	Wang, M., Roberts, D.L., Paschke, R., Shea, T.M., Masters, B.S. and Kim, J.J. Three-dimensional structure of NADPH-cytochrome P450 reductase: prototype for FMN- and FAD-containing enzymes. Proc. Natl. Acad. Sci. USA 94 (1997) 8411–8416. [DOI] [PMID: 9237990]
9.	Munro, A.W., Noble, M.A., Robledo, L., Daff, S.N. and Chapman, S.K. Determination of the redox properties of human NADPH-cytochrome P450 reductase. Biochemistry 40 (2001) 1956–1963. [DOI] [PMID: 11329262]
10.	Gutierrez, A., Grunau, A., Paine, M., Munro, A.W., Wolf, C.R., Roberts, G.C. and Scrutton, N.S. Electron transfer in human cytochrome P450 reductase. Biochem. Soc. Trans. 31 (2003) 497–501. [DOI] [PMID: 12773143]

[EC 1.6.2.4 created 1972, modified 2003]