Gas-phase fragmentation of deprotonated tryptophan and its clusters [Trpn-H]- induced by different activation methods

Abstract

Rationale Non-covalent amino acid clusters are the subject of intense research in diverse areas including peptide bond formation studies or the determination of proton affinities or methylating abilities of amino acids. However, most of the research has focused on positive ions and little is known about anionic clusters. Methods Fragmentation reactions of deprotonated tryptophan (Trp), [Trp-H]- and Trp singly deprotonated non-covalently bound clusters [Trpn-H]-, n=2, 3, 4, were investigated using low-energy collision-induced dissociation (CID) with He atoms, high-energy CID with Na atoms, and electron-induced dissociation (EID) with 20-35 eV electrons. Fragmentation of the monomeric Trp anio..