Comparing Mass Spectrometric Characteristics of Peptides and Peptoids—2†

✍ Scribed by Heerma, Wigger; Boon, Jean-Paul J. L.; Versluis, Cornelis; Kruijtzer, John A. W.; Hofmeyer, Lovina J. F.; Liskamp, Rob M. J.

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 568 KB
• Volume: 32
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/(sici)1096-9888(199707)32:7<697::aid-jms521>3.0.co;2-u

✦ Synopsis

The high-energy collision-induced dissociation (CID) spectra of the [ M + H ] ' and [ M Ô H ]ions of substance P fragment 6-11, the retropeptide and the corresponding peptoid and retropeptoid were compared. The CID spectra of the [ M + H ] ' ion of the corresponding (retro)peptide and (retro)peptoid exhibit both B-and Y/-type sequence ions at identical m/z-values. The di †erences in the relative abundances of these sequence ions, however, can be related to structural characteristics of the compounds. The fragmentation behaviour of the N-substituted immonium ions di †ers from that of the immonium ions derived from common amino acids by showing a preferential loss of a imine molecule. This dominant fragmentation reaction is suppressed in the CID spec-CH 2 xNH trum of the N-substituted glutamine immonium ion in favour of a less energy demanding cyclization reaction involving the loss of

The CID spectra of the [ M Ô H ]ions of both peptides and peptoids show C-type ions, NH 3 . which appeared to be more abundant in the spectra of the peptides than in those of the peptoids. C-Terminal /Zand Y-type ions are characteristic of the peptides, whereas the peptoid spectra show relatively abundant N-terminal /B-type ions. Both [ M + H ] ' and [ M Ô H ]ion CID spectra show loss of amino acid-speciÐc side-chains, which occurs as radical loss in the case of peptides and as molecular loss in peptoids. 1997