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 (FMN, FAD) containing both FMN and FAD. 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. The enzyme catalyses the reduction of the heme-thiolate-dependent monooxygenases, such as EC, unspecific monooxygenase and reduction of EC, heme oxygenase (decyclizing). It is part of the microsomal hydroxylating system. It also reduces cytochrome b5 and cytochrome c.

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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