Using guided ion beam tandem mass spectrometry, the kinetic energy dependence of the absolute cross sections for fragmentation of protonated peptides in collision-induced dissociation have been examined. Analysis of such data permits the determination of the rate-limiting energies for the multitude of pathways observed in these dissociations and also allows these pathways to be assigned to either loose or tight transition states. To explore the mechanisms for the fragmentation pathways observed, potential energy surfaces are evaluated computationally and can be validated by comparison with the experimental data. Generally good agreement is found between theory (given an adequate level and basis set) and experiment although even relative energies between various channels are not uniformly predicted with accuracy.

Peptide fragmentation: From dynamics and kinetics to potential energy surfaces

256th National Meeting (2018)

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