Electron capture dissociation of multiply charged peptide cations

Abstract

For five 12- to 17-mer multiply charged peptide cations, capture of low energy electrons yields unique products, mainly c and z· ions from amine bond cleavage. Their mass values for m > 400 define the complete sequence for two peptides, all but the ordering of a doublet in another, and all but the partial ordering of a triplet in the other two. The mass values from collisionally activated dissociation (CAD), on the other hand, indicate cleavages of 33 amide bonds (b and y ion products) of the 68 possible bonds between the amino acids of these peptides. Because the other common methods for ion dissociation yield products similar to those from CAD, electron capture dissociation (ECD) should provide a valuable complementary technique for sequencing of multiply charged peptide cations.