Deamidation Reactions of Asparagine- and Glutamine-Containing Dipeptides Investigated by Ion Spectroscopy.

ABSTRACT: Deamidation is a major fragmentation channel upon activation by collision induced dissociation (CID) for protonated peptides containing glutamine (Gln) and asparagine (Asn) residues. Here, we investigate these NH₃-loss reactions for four Asn- and Gln-containing protonated peptides in terms of the resulting product ion structures using infrared ion spectroscopy with the free electron laser FELIX. The influence of the side chain length (Asn versus Gln) and of the amino acid sequence on the deamidation reaction has been examined. Molecular structures for the product ions are determined by comparison of experimental IR spectra with spectra predicted by density functional theory (DFT). The reaction mechanisms identified for the four dipeptides AlaAsn, AsnAla, AlaGln, and GlnAla are n

SUBMITTER: Kempkes LJ 

PROVIDER: S-EPMC5059420 | biostudies-literature | 2016 Nov

REPOSITORIES: biostudies-literature