Infrared Multiple-Photon Dissociation Action Spectroscopy of the b₂⁺ Ion from PPG: Evidence of Third Residue Affecting b₂⁺ Fragment Structure.

ABSTRACT: Infrared multiple-photon dissociation (IRMPD) action spectroscopy was performed on the b₂⁺ fragment ion from the protonated PPG tripeptide. Comparison of the experimental infrared spectrum with computed spectra for both oxazolone and diketopiperazine structures indicates that the majority of the fragment ion population has an oxazolone structure with the remainder having a diketopiperazine structure. This result is in contrast with a recent study of the IRMPD action spectrum of the PP b₂⁺ fragment ion from PPP, which was found to be nearly 100% diketopiperazine (Martens et al. Int. J. Mass Spectrom. 2015, 377, 179). The diketopiperazine b₂⁺ ion is thermodynamically more stable than the oxazolone but normally requires a trans

SUBMITTER: Poutsma JC 

PROVIDER: S-EPMC5484043 | biostudies-literature | 2017 Jul

REPOSITORIES: biostudies-literature