Investigation of c ions formed by N-terminally charged peptides upon collision-induced dissociation.

Tandem spectrometry is one of most powerful and versatile tools for peptide and protein structure elucidation. Low-energy CID is by far the most popular and readily accessible activation method to generate high fragmentation efficiency and complementary sequence information for protonated peptides. CID is classically characterized by amide bond cleavage and the formation of typical b/y ions where the observation of c ions is scarce. In this perspective special feature article, Prof. Xinhua Guo and co-workers evaluate the influence of changing an arginine residue for a deuterohemin group at the peptide N-terminal on the formation of c ions upon low-energy CID. Results demonstrate that the N-terminal fixed charge of peptides promotes the formation of c ions either by direct cleavage from precursor ions or through the further dissociation of uncommon b ions via a McLafferty-type rearrangement. Dr. Xinhua Guo is professor of chemistry at Jilin University (China). Her research interests are in fundamental and applied mass spectrometry more specifically understanding the behavior of biomolecule fragmentation.