Ion activation and dissociations of the cyclic peptide c-(Lys-D-His-beta-Ala-His) and its Cu(I), Cu(II) and Cu(III) complexes: ECD and CID experiments

摘要

This work presents for the first time the behavior of a cationized cyclic peptide under ECD and SORI-CID . Depending on the pH and on declustering potentials, different copper ion oxidation states can be produced. In particular the formation of Cu(III) has been evidenced under basic conditions. A quite different behavior is observed in both CID and ECD conditions as a function of the oxidation state of the metal ion but the observed product ions are mainly the same from species bearing a copper with the same charge state. Some ions are specific for the ECD mode, in particular those at m/z 328.2 and m/z 365.1. To rationalize the experimental data fragmentation pathways have been proposed.