Sequencing of argentinated peptides by means of electrospray tandem mass spectrometry

A strategy for semiautomatic sequencing of argentinated (silver-containing) oligopeptides has been developed. Sequencing is based on a search algorithm that identifies a triplet peak relationship in a production spectrum of the [M + Ag](+) ion of an oligopeptide. The ions that constitute a triplet are [b(n) + OH + Ag](+), [b(n) - H + Ag](+), and [a(n) - H + Ag](+), which are separated by 18 and 28 m/z units, respectively. The difference in the m/z values of adjacent triplets identifies the residue that is "cleaved", Observation of the [y(n) + H + Ag](+) ion containing the cleaved residue confirms the assignment. Sequencing of argentinated tryptic peptides may prove useful for automated proteome analysis via the sequence tag method.