EC - Ribosyldihydronicotinamide dehydrogenase (quinone)

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IntEnz Enzyme Nomenclature


Accepted name:
ribosyldihydronicotinamide dehydrogenase (quinone)
Other names:
NRH:quinone oxidoreductase 2
NAD(P)H:quinone oxidoreductase-2 [misleading]
quinone reductase 2
N-ribosyldihydronicotinamide dehydrogenase (quinone)
NAD(P)H:quinone oxidoreductase2 [misleading]
Systematic name:
1-(β-D-ribofuranosyl)-1,4-dihydronicotinamide:quinone oxidoreductase




A flavoprotein. Unlike EC, NAD(P)H dehydrogenase (quinone), this quinone reductase cannot use NADH or NADPH; instead it uses N-ribosyl- and N-alkyldihydronicotinamides. Polycyclic aromatic hydrocarbons, such as benz[a]anthracene, and the estrogens 17β-estradiol and diethylstilbestrol are potent inhibitors, but dicoumarol is only a very weak inhibitor [2]. This enzyme can catalyse both 2-electron and 4-electron reductions, but one-electron acceptors, such as potassium ferricyanide, cannot be reduced [3].

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , DIAGRAM , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Structural data: CSA , EC2PDB
CAS Registry Number: 667919-86-0


  1. Liao, S., Dulaney, J.T. and Williams-Ashman, H.G.
    Purification and properties of a flavoprotein catalyzing the oxidation of reduced ribosyl nicotinamide.
    J. Biol. Chem. 237: 2981-2987 (1962). [PMID: 14465018]
  2. Zhao, Q., Yang, X.L., Holtzclaw, W.D. and Talalay, P.
    Unexpected genetic and structural relationships of a long-forgotten flavoenzyme to NAD(P)H:quinone reductase (DT-diaphorase)
    Proc. Natl. Acad. Sci. USA 94: 1669-1674 (1997). [PMID: 9050836]
  3. Wu, K., Knox, R., Sun, X.Z., Joseph, P., Jaiswal, A.K., Zhang, D., Deng, P.S.-K. and Chen, S.
    Catalytic properties of NAD(P)H:quinone oxidoreductase-2 (NQO2), a dihydronicotinamide riboside dependent oxidoreductase.
    Arch. Biochem. Biophys. 347: 221-228 (1997). [PMID: 9367528]
  4. Jaiswal, A.K.
    Human NAD(P)H:quinone oxidoreductase2. Gene structure, activity, and tissue-specific expression.
    J. Biol. Chem. 269: 14502-14508 (1994). [PMID: 8182056]

[EC created 2005 as EC, transferred 2015 to EC]