Fragmentation of Cu(II)-peptide complexes as a route to molecular radical cations of peptides

Abstract

The fragmentation of Cu(II)-peptide complexes as a route to molecular radial cations of peptides was analyzed. A PE SCIEX Q/STAR hybrid quadrupole / time-of-flight tandem mass spectrometer and PESCIEX API 3000 prototype triple quadrupole mass spectrometer were used for the investigation. It was found that abundant M+ ions can be produced from some tryosinyl- and tryptophanyl-bearing oligopeptides. It was observed that the presence of the tyrosine or a tryptophan residue resulted in significant reduction of the fragmentation barrier of the radical formation channel.