Radiation- and Photo-Induced Oxidation Pathways of Methionine in Model Peptide Backbone under Anoxic Conditions |
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Authors: | Tomasz P dzinski,Katarzyna Grzyb,Konrad Skotnicki,Piotr Filipiak,Krzysztof Bobrowski,Chryssostomos Chatgilialoglu,Bronislaw Marciniak |
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Affiliation: | 1.Center for Advanced Technology, Adam Mickiewicz University, Uniwersytetu Poznanskiego 10, 61-614 Poznan, Poland; (T.P.); (P.F.);2.Faculty of Chemistry, Adam Mickiewicz University, Uniwersytetu Poznanskiego 8, 61-614 Poznan, Poland;3.Institute of Nuclear Chemistry and Technology, Dorodna 16, 03-195 Warsaw, Poland;4.ISOF, Consiglio Nazionale delle Ricerche, Via P. Gobetti 101, 40129 Bologna, Italy |
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Abstract: | Within the reactive oxygen species (ROS) generated by cellular metabolisms, hydroxyl radicals (HO•) play an important role, being the most aggressive towards biomolecules. The reactions of HO• with methionine residues (Met) in peptides and proteins have been intensively studied, but some fundamental aspects remain unsolved. In the present study we examined the biomimetic model made of Ac-Met-OMe, as the simplest model peptide backbone, and of HO• generated by ionizing radiation in aqueous solutions under anoxic conditions. We performed the identification and quantification of transient species by pulse radiolysis and of final products by LC-MS and high-resolution MS/MS after γ-radiolysis. By parallel photochemical experiments, using 3-carboxybenzophenone (CB) triplet with the model peptide, we compared the outcomes in terms of short-lived intermediates and stable product identification. The result is a detailed mechanistic scheme of Met oxidation by HO•, and by CB triplets allowed for assigning transient species to the pathways of products formation. |
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Keywords: | methionine, oxidation, pulse and γ -radiolysis, laser flash and steady-state photolysis, free radicals, high-resolution MS/MS |
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