IUBMB Enzyme Nomenclature


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, 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


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.

5. Williams, C.H.,Jr. and Kamin, H. Microsomal triphosphopyridine nucleotide-cytochrome c reductase in liver. J. Biol. Chem. 237, (1962) 587-595. p> 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. [PMID: 8589067]

8. Wang, M., Roberts, D.L., Paschke, R., Shea, T.M., Masters, B.S.S. and Kim, J.-J.P. Three-dimensional structure of NADPH-cytochrome P450 reductase: Prototype for FMN- and FAD-containing enzymes. Proc. Natl. Acad. Sci. USA 94, (1997) 8411-8416. [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. [PMID: 11329262]

10. Gutierrez, A., Grunau, A., Paine, M., Munro, A.W., Wolf, C.R., Roberts, G.C.K. and Scrutton, N.S. Electron transfer in human cytochrome P450 reductase. Biochem. Soc. Trans. 31, (2003) 497-501. [PMID: 12773143]

[EC created 1972, modified 2003]

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