Electron capture dissociation of multiply charged peptide cations

For five 12- to 17-mer multiply charged peptide cations, capture of low ene rgy electrons yields unique products, mainly c and z(.) ions from amine bon d cleavage. Their mass values for m > 400 define the complete sequence for two peptides, all but the ordering of a doubler in another, and all but the partial ordering of a triplet in the other two. The mass values from colli sionally activated dissociation (CAD), on the other hand, indicate cleavage s 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 io n dissociation yield products similar to those from CAD, electron capture d issociation (ECD) should provide a valuable complementary technique for seq uencing of multiply charged peptide cations. (Int J Mass Spectrom 185/18611 87 (1999) 787-793) (C) 1999 Elsevier Science B.V.