IntEnz

EC 1.6.2.4 - NADPH—hemoprotein reductase

IntEnz Enzyme Nomenclature
EC 1.6.2.4

Names

Reaction

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

Cofactors

• FMN
• FAD

Comments:

A flavoprotein containing both FMN and FAD. This enzyme catalyses the transfer of electrons from NADPH, an obligatory two-electron donor, to microsomal P450 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

References

1. Haas, E., Horecker, B.L. and Hogness, T.R.
   The enzymatic reduction of cytochrome c, cytochrome c reductase.
   J. Biol. Chem. 136 : 747-774 (1940).
2. Horecker, B.L.
   Triphosphopyridine nucleotide-cytochrome c reductase in liver.
   J. Biol. Chem. 183 : 593-605 (1950).
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 : 3714-3721 (1969). [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 : 921-931 (1965).
5. Williams, C.H.,Jr. and Kamin, H.
   Microsomal triphosphopyridine nucleotide-cytochrome c reductase in liver.
   J. Biol. Chem. 237 : 587-595 (1962). [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 : 4081-4088 (1965). [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 : 562-572 (1995). [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 : 8411-8416 (1997). [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 : 1956-1963 (2001). [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 : 497-501 (2003). [PMID: 12773143]

[EC 1.6.2.4 created 1972, modified 2003]