Mass spectrometric differentiation of helical peptides containing D-amino acids by MS/MS and ion mobility MS

摘要

1. The KLA-peptides used in this study are based on the well-characterized sequence acetyl-KLALKLALxxLKLALKLA-amide which exhibits a high intrinsic α-helical propensity. D-amino acids destabilize the helix, leading to a decrease of helicity as shown by previous CD and NMR experiments. 2. The incorporation of two adjacent D-amino acids results in changes of the characteristic collision energy in the range of -1 to 2.5 eV and is throughout accompanied by an increased formation of b9 and y9 ions indicating a preferred fragmentation at the position of the D-amino acids. 3. Ion mobility experiments show that most of the peptide isomers can be separated. However, no correlation between the ion mobility behaviour and the structural (helical) propensity of incorporated amino acid could be found.