title: X-ray radiation-induced addition of oxygen atoms to protein residues.
abstract: The additions of oxygen and peroxide to residues that result when proteins are exposed to the free radicals produced using the Fenton reaction or X-rays have been studied for over a century. Nevertheless little is known about the impact these modifications have on protein crystal structures. Here evidence is presented that both kinds of modifications occur in protein crystals on a significant scale during the collection of X-ray diffraction data. For example, at least 538 of the 5,351 residues of protein molecules in the crystal used to obtain the structure for photosystem II described by the PDB accession number 3ARC became oxygenated during data collection.
authors.affiliation: Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, 06520.
authors.forename: Jimin
authors.initials: J
authors.lastname: Wang
mesh_terms: D018360:Crystallography, X-Ray; D030562:Databases, Protein; D008958:Models, Molecular; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D045332:Photosystem II Protein Complex / Q000737:chemistry / Q000528:radiation effects; D011487:Protein Conformation; D013816:Thermodynamics; D014961:X-Ray Diffraction; D014965:X-Rays
chemical_list: D045332:Photosystem II Protein Complex; D010100:Oxygen
keywords: X-ray crystallography; direct methods; normalized electron density E-maps; phase problem; photosystem II; radiation chemistry