Structures of mammalian cytosolic quinone reductases

Free Radic Biol Med. 2000 Aug;29(3-4):241-5. doi: 10.1016/s0891-5849(00)00299-9.


The metabolism of quinone compounds presents one source of oxidative stress in mammals, as many pathways proceed by mechanisms that generate reactive oxygen species as by-products. One defense against quinone toxicity is the enzyme NAD(P)H:quinone oxidoreductase type 1 (QR1), which metabolizes quinones by a two-electron reduction mechanism, thus averting production of radicals. QR1 is expressed in the cytoplasm of many tissues, and is highly inducible. A closely related homologue, quinone reductase type 2 (QR2), has been identified in several mammalian species. QR2 is also capable of reducing quinones to hydroquinones, but unlike QR1, cannot use NAD(P)H. X-ray crystallographic studies of QR1 and QR2 illustrate that despite their different biochemical properties, these enzymes have very similar three-dimensional structures. In particular, conserved features of the active sites point to the close relationship between these two enzymes.

Publication types

  • Research Support, U.S. Gov't, P.H.S.
  • Review

MeSH terms

  • Animals
  • Binding Sites
  • Coenzymes / metabolism
  • Crystallography, X-Ray
  • Cytosol / enzymology*
  • Humans
  • Metals / metabolism
  • Models, Molecular
  • Protein Conformation
  • Quinone Reductases / chemistry*
  • Quinone Reductases / metabolism
  • Quinones / metabolism


  • Coenzymes
  • Metals
  • Quinones
  • Quinone Reductases