title: Radical production from free and peptide-bound methionine sulfoxide oxidation by peroxynitrite and hydrogen peroxide/iron(II).
abstract: Methionine sulfoxide is a post-translational protein modification that has been receiving increasing attention in the literature. Here we used electron paramagnetic resonance spin trapping techniques to show that free and peptide-bound methionine sulfoxide is oxidized by hydrogen peroxide/iron(II)-EDTA and peroxynitrite through the intermediacy of the hydroxyl radical to produce both *CH3 and *CH2CH2CH radicals. The results indicate that methionine sulfoxide residues are important targets of reactive oxygen- and nitrogen-derived species in proteins. Since the produced protein-derived radicals can propagate oxidative damage, the results add a new antioxidant route for the action of the enzyme peptide methionine sulfoxide reductase.
authors.affiliation: Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, C.P. 26077, 05513-970, São Paulo, SP, Brazil.
authors.forename: Lia S
authors.initials: LS
authors.lastname: Nakao
authors.forename: Leo K
authors.initials: LK
authors.lastname: Iwai
authors.forename: Jorge
authors.initials: J
authors.lastname: Kalil
authors.forename: Ohara
authors.initials: O
authors.lastname: Augusto
mesh_terms: D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals; D006861:Hydrogen Peroxide; D007501:Iron; D008715:Methionine / Q000031:analogs & derivatives* / Q000737:chemistry*; D008968:Molecular Conformation; D010084:Oxidation-Reduction; D010455:Peptides / Q000737:chemistry*; D030421:Peroxynitrous Acid
chemical_list: D005609:Free Radicals; D010455:Peptides; D030421:Peroxynitrous Acid; D008715:Methionine; D006861:Hydrogen Peroxide; D007501:Iron; C013111:methionine sulfoxide