Activation of photo-induced radicals: a tool for protein identification

The radicals produced by laser irradiation can be trapped in the trap (MS ² ) and then re-excited by collision activation (MS ³ ). The activation of a radical ion leads to fragmentation mechanisms that are very different from those observed in a non-radical ion. In particular, it is possible to break covalent bonds (especially those in the backbone) while preserving weak bonds, which is particularly relevant for the study of non-covalent complexes or post-translational modifications.