Generation and Dissociation of Cationic and Anionic Radical Peptides

摘要

Collision-induced dissociation (CID) of Copper(II)-peptide complexes results in efficient formation of peptide radical cations (M~((centre dot)+)). We describe the use of a prototypical system to explore the fundamental factors that govern the formation and dissociation of M~((centre dot)+) peptide ions, and to generate aliphatic-only and alpha-radical cationic peptides. An extension of the strategy allowed the production of [M+H]~((centre dot)2+) and [M-2H]~((centre dot)-).^sWe have examined the influences of the sequence and the position of the radical site in the radical cationic angiotensin analogs on their dissociation pathways. CID spectra of peptide radical cations are strikingly different from the spectra obtained for the corresponding even-electron [M+H]~((centre dot)+) species. M~((centre dot)+) ions undergo facile side chain cleavages and preferentially produce a_(n) and z_(n), backbone fragments.