Structures of Recombinant Mouse and Human Nad(P)H:Quinone Oxidoreductases:Species Comparison and Structural Changes with Substrate Binding and ReleaseFaig, M., Bianchet, M.A., Chen, S., Winski, S., Ross, D., Talalay, P., Amzel, L.M.
(2000) Proc.Natl.Acad.Sci.USA 97: 3177
- PubMed: 10706635
- DOI: 10.1073/pnas.050585797
- Primary Citation of Related Structures:
- Also Cited By: 1H69, 1H66
- PubMed Abstract:
- The Three-Dimensional Structure of Nad(P)H:Quinone Reductase, a Flavoprotein Involved in Cancer Chemoprotection and Chemotherapy: Mechanism of Two-Electron Reduction
Li, R.,Bianchet, M.A.,Talalay, P.,Amzel, L.M.
(1995) Proc.Natl.Acad.Sci.USA 92: 8846
- Crystal Structure of Human Quinone Reductase Type 2, a Metalloprotein
Foster, C.,Bianchet, M.A.,Talalay, P.,Zhao, Q.,Amzel, L.M.
(1999) Biochemistry 38: 9881
- Structure and Mechanism of Cytosolic Quinone Reductase
Bianchet, M.A.,Foster, C.,Faig, M.,Talalay, P.,Amzel, L.M.
(1999) Biochem.Soc.Trans. 27: 610
NAD(P)H/quinone acceptor oxidoreductase (QR1, NQO1, formerly DT-diaphorase; EC ) protects animal cells from the deleterious and carcinogenic effects of quinones and other electrophiles. In this paper we report the apoenzyme structures of human (at 1. ...
NAD(P)H/quinone acceptor oxidoreductase (QR1, NQO1, formerly DT-diaphorase; EC ) protects animal cells from the deleterious and carcinogenic effects of quinones and other electrophiles. In this paper we report the apoenzyme structures of human (at 1.7-A resolution) and mouse (2.8 A) QR1 and the complex of the human enzyme with the substrate duroquinone (2.5 A) (2,3,5, 6-tetramethyl-p-benzoquinone). In addition to providing a description and rationale of the structural and catalytic differences among several species, these structures reveal the changes that accompany substrate or cofactor (NAD) binding and release. Tyrosine-128 and the loop spanning residues 232-236 close the binding site, partially occupying the space left vacant by the departing molecule (substrate or cofactor). These changes highlight the exquisite control of access to the catalytic site that is required by the ping-pong mechanism in which, after reducing the flavin, NAD(P)(+) leaves the catalytic site and allows substrate to bind at the vacated position. In the human QR1-duroquinone structure one ring carbon is significantly closer to the flavin N5, suggesting a direct hydride transfer to this atom.
Departments of Biophysics and Biophysical Chemistry and Pharmacology and Molecular Sciences, Johns Hopkins Medical School, Baltimore, MD 21205, USA.