Fragmentation of deprotonated N-benzoylpeptides: Formation of deprotonated oxazolones

  • Alex G. HarrisonEmail author
  • Alex B. Young


The fragmentation reactions of deprotonated N-benzoyl peptides, specifically hippurylglycine, hippurylglyclyclycine, and hippurylphenylalanine (hippuryl = N-benzoylGly) have been studied using MS2 and MS3 experiments as well as deuterium labeling. A major fragment ion is observed at m/z 160 ([C9H6NO2]) which, upon collisional activation, mainly eliminates CO2 indicating that the two oxygen atoms have become bonded to the same carbon. This observation is rationalized in terms of formation of deprotonated 2-phenyl-5-oxazolone. Various pathways to the deprotonated oxazolone have been elucidated through MS3 experiments. Fragmentation of deprotonated N-acetylalanylalanine gives a relatively weak signal at m/z 112 which, upon collisional activation, fragments, in part, by loss of CO2 leading to the conclusion that the m/z 112 ion is deprotonated 2,4-dimethyl-5-oxazolone.


Fragmentation Reaction Collisional Activation Oxazolone Protonated Peptide Labile Hydrogen 
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Copyright information

© American Society for Mass Spectrometry 2004

Authors and Affiliations

  1. 1.Department of ChemistryUniversity of TorontoTorontoCanada

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