EC - NADPH:quinone reductase

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IntEnz Enzyme Nomenclature


Accepted name:
NADPH:quinone reductase
Other names:
quinone oxidoreductase
NADPH2:quinone oxidoreductase
Systematic name:
NADPH:quinone oxidoreductase




a zinc enzyme, specific for NADPH. Catalyses the one-electron reduction of certain quinones, with the orthoquinones 1,2-naphthoquinone and 9,10-phenanthrenequinone being the best substrates [1]. Dicoumarol [cf. EC NAD(P)H dehydrogenase (quinone)] and nitrofurantoin are competitive inhibitors with respect to the quinone substrate. The semiquinone free-radical product may be non-enzymically reduced to the hydroquinone or oxidized back to quinone in the presence of O2 [1]. In some mammals the enzyme is abundant in the lens of the eye, where it is identified with the protein ζ-crystallin.

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Protein domains and families: PROSITE:PDOC00058
Structural data: CSA , EC2PDB
Gene Ontology: GO:0003960
CAS Registry Number: 9032-20-6
UniProtKB/Swiss-Prot: (16) [show] [UniProt]


  1. Rao, P.V., Krishna, C.M. and Zigler, J.S., Jr.
    Identification and characterization of the enzymatic activity of ζ-crystallin from guinea pig lens. A novel NADPH:quinone oxidoreductase.
    J. Biol. Chem. 267 : 96-102 (1992). [PMID: 1370456]
  2. Duhaiman, A.S.
    Kinetic properties of camel lens ζ-crystallin.
    Int. J. Biochem. Cell Biol. 28 : 1163-1168 (1996). [PMID: 8930141]
  3. Bazzi, M.D.
    Interaction of camel lens ζ-crystallin with quinones: portrait of a substrate by fluorescence spectroscopy.
    Arch. Biochem. Biophys. 395 : 185-190 (2001). [PMID: 11697855]
  4. Tang, A. and Curthoys, N.P.
    Identification of ζ-crystallin/NADPH:quinone reductase as a renal glutaminase mRNA pH response element-binding protein.
    J. Biol. Chem. 276 : 21375-21380 (2001). [PMID: 11294877]

[EC created 1999]