A linear free-energy correlation in the low-energy tandem mass spectra of protonated tripeptides Gly–Gly–Xxx

✍ Scribed by Daniel G. Morgan; Maurice M. Bursey

• Publisher: John Wiley and Sons
• Year: 1994
• Tongue: English
• Weight: 437 KB
• Volume: 29
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/oms.1210290705

✦ Synopsis

Abstract

The backbone cleavages of protonated tripeptide ions of the series Gly—Gly—Xxx, where Xxx  Gly, Ala, Val, d‐Leu, l‐Leu, Ile, Phe, Tyr, Trp, Pro, Met and Glu, were studied in a hybrid tandem mass spectrometer. C‐Terminal y‐type ions and N‐terminal a‐ and b‐type ions were noted. A linear relationship between log (y~1~/b~2~) and the proton affinity of the C‐terminal amino acid substituents was found: as the proton affinity of the C‐terminal residue increases, the fraction of y~1~ ion formation increases. When the C‐terminal substituent was more basic than Trp, the b~2~ ion was not observed. It is likely that the site of protonation changes from peptide bond to side‐chain for just these residues, Lys, His and Arg.