Comparing Mass Spectrometric Characteristics of Peptides and Peptoids

✍ Scribed by W. Heerma; C. Versluis; C. G. de Koster; J. A. W. Kruijtzer; I. Zigrovic; R. M. J. Liskamp

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 500 KB
• Volume: 10
• Category: Article
• ISSN: 0951-4198
• DOI: 10.1002/(sici)1097-0231(19960315)10:4<459::aid-rcm501>3.0.co;2-j

✦ Synopsis

The collision-induced disociation (CID) spectra of the [M+H]+ ions of a pentapeptide and the corresponding peptoid and retropeptoid have been compared. The spectra of the peptide and peptoid both exhibit Band Ytype sequence ions at identical m/z values. In contrast to the peptide, the [M+H]' ion of the peptoid and all sequence ions containing an N-substituted glycine derivative corresponding to a tyrosine amino acid residue can easily lose a C&O molecule in a charge-remote fragmentation process. The presence of N-substituted glycine residues in a peptoid is further apparent from the presence of N-substituted immonium ions, which differ significantly in their fragmentation behaviour from the corresponding immonium ions observed in the spectra of common oligopeptides. Loss of the CH,=NH imine molecule is the dominant fragmentation reaction in the CID spectra of all peptoid immonium ions investigated in this study. The elimination of the CH=NH2 ylide analogue from common peptide immonium ions is energetically less favourable as shown by ab initio calculations. The relative heat of formation of the CH=NH, ylide neutral appeared to be 168 kJ mol-' more than that of the CH,=NH imine molecule.