Sequencing of argentinated peptides by means of electrospray tandem mass spectrometry

Abstract

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 product ion 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] +, 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.