title: Crystal structure of peroxynitrite-modified bovine Cu,Zn superoxide dismutase.
abstract: The crystal structure of bovine Cu,Zn superoxide dismutase modified with peroxynitrite (ONOO-) was determined by X-ray diffraction, utilizing the existing three-dimensional model of the native structure deposited in the Brookhaven Protein Data Bank (J. A. Tainer et al., J. Mol. Biol. 160, 181-217, 1982). The native structure and the modified derivative were refined to R factors of 19.0 and 18.7% respectively using diffraction data from 6.0 to 2.5 A. The major result after reaction with peroxynitrite was the appearance of electron density 1.45 A from a single epsilon carbon of Tyr-108, the only tyrosine residue in the sequence. Tyr-108 is a solvent-exposed residue 18 A from the copper atom in the active site. The electron density was consistent with nitration of Tyr-108 at one of the epsilon carbons to form 3-nitrotyrosine. We propose that the nitration occurs in solution by transfer of a nitronium-like species from the active site on one superoxide dismutase dimer to the Tyr-108 of a second dimer.
authors.affiliation: Center for Macromolecular Crystallography, School of Medicine, University of Alabama, Birmingham 35294.
authors.forename: C D
authors.initials: CD
authors.lastname: Smith
authors.forename: M
authors.initials: M
authors.lastname: Carson
authors.forename: M
authors.initials: M
authors.lastname: van der Woerd
authors.forename: J
authors.initials: J
authors.lastname: Chen
authors.forename: H
authors.initials: H
authors.lastname: Ischiropoulos
authors.forename: J S
authors.initials: JS
authors.lastname: Beckman
mesh_terms: D000818:Animals; D001665:Binding Sites; D002417:Cattle; D003196:Computer Graphics; D003461:Crystallography; D005971:Glutamates / Q000737:chemistry; D066298:In Vitro Techniques; D008958:Models, Molecular; D009566:Nitrates / Q000737:chemistry*; D009573:Nitrites; D017434:Protein Structure, Tertiary; D013482:Superoxide Dismutase / Q000737:chemistry*; D014443:Tyrosine / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D005971:Glutamates; D009566:Nitrates; D009573:Nitrites; C039642:peroxynitric acid; D014443:Tyrosine; D013482:Superoxide Dismutase