Reaction: NADPH + H+ + a quinone = NADP+ + a quinol
Other name(s): reduced nicotinamide adenine dinucleotide phosphate (quinone) dehydrogenase; NADPH oxidase; NADPH2 dehydrogenase (quinone)
Systematic name: NADPH:(quinone-acceptor) oxidoreductase
Comments: A flavoprotein [1, 2]. The enzyme from Escherichia coli is specific for NADPH and is most active with quinone derivatives and ferricyanide as electron acceptors [3]. Menaquinone can act as acceptor. The enzyme from hog liver is inhibited by dicoumarol and folic acid derivatives but not by 2,4-dinitrophenol [1].
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 37256-37-4
References:
1. Koli, A.K., Yearby, C., Scott, W. and Donaldson, K.O. Purification and properties of three separate menadione reductases from hog liver. J. Biol. Chem. 244 (1969) 621-629. [PMID: 4388793]
2. Hayashi, M., Hasegawa, K., Oguni, Y. and Unemoto, T. Characterization of FMN-dependent NADH-quinone reductase induced by menadione in Escherichia coli. Biochim. Biophys. Acta 1035 (1990) 230-236. [PMID: 2118386]
3. Hayashi, M., Ohzeki, H., Shimada, H. and Unemoto, T. NADPH-specific quinone reductase is induced by 2-methylene-4-butyrolactone in Escherichia coli. Biochim. Biophys. Acta 1273 (1996) 165-170. [PMID: 8611590]