title: Structures of mammalian cytosolic quinone reductases.
abstract: 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.
authors.affiliation: Department of Biophysics and Biophysical Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
authors.forename: C E
authors.initials: CE
authors.lastname: Foster
authors.forename: M A
authors.initials: MA
authors.lastname: Bianchet
authors.forename: P
authors.initials: P
authors.lastname: Talalay
authors.forename: M
authors.initials: M
authors.lastname: Faig
authors.forename: L M
authors.initials: LM
authors.lastname: Amzel
mesh_terms: D000818:Animals; D001665:Binding Sites; D003067:Coenzymes / Q000378:metabolism; D018360:Crystallography, X-Ray; D003600:Cytosol / Q000201:enzymology*; D006801:Humans; D008670:Metals / Q000378:metabolism; D008958:Models, Molecular; D011487:Protein Conformation; D011808:Quinone Reductases / Q000737:chemistry* / Q000378:metabolism; D011809:Quinones / Q000378:metabolism
chemical_list: D003067:Coenzymes; D008670:Metals; D011809:Quinones; D011808:Quinone Reductases