The numerous damages induced on proteins during oxidative stress are often responsible for pathologies. Indeed, the damages from protein oxidation are sometimes used as biomarkers within tissues and biological fluids. These oxidations result from attacks by reactive oxygen species, particularly the hydroxyl radical. In this context, our team focuses on radio-induced modifications at the level of aromatic amino acids (Tyr and Trp) through the oxidation of peptides and free amino acids in solution, isolated proteins, as well as protein complexes such as human centrin 2 (CEN2) [Gatin2021] and Xeroderma Pigmentosum (XPC) or prion protein [Bohl2020]. The approaches used involve the controlled generation of oxidizing radicals (hydroxyl radical or superoxide ion) and then the identification of structural modifications. By combining ultra-high-pressure liquid chromatography with mass spectrometry detection, coupled with isotopic exchanges [Gatin2022] [Billault2022], we were able to highlight new structures of tyrosine dimers as well as new oxidations of tyrosine, whether within peptides, isolated proteins, or during protein-protein cross-linking. These new structures suggest a modification of the tertiary structure of proteins.

Schematic Representation of Oxidative Dimerization of Tyrosine Residues within a Protein.