Bond cleavage reactions in the tripeptide trialanine upon free electron capture*
Institut für Ionenphysik und Angewandte Physik and Center of
Molecular Biosciences Innsbruck, Universität Innsbruck , Technikerstr. 25, 6020
Received: 19 December 2013
Received in final form: 7 March 2014
Published online: 9 May 2014
In the present study we performed dissociative electron attachment (DEA) measurements with the tripeptide trialanine, C9H17N3O4, utilizing a crossed electron-molecular beam experiment with high electron energy resolution (~100 meV). Anion efficiency yields as a function of the incident electron energy are obtained for the most abundant anions up to electron energies of ~4 eV. Quantum chemical calculations are performed to determine the thermochemical thresholds for the anions observed in the measurements. There is no evidence of a molecular anion with lifetime of mass spectrometric timescales. The dehydrogenated closed shell anion (M-H)− is one of the fragment anions observed for which the calculations show that H-loss is energetically possible from carboxyl, as well as amide groups. In contrast to the dipeptide dialanine and monomer alanine the cleavage of the N-Cα bond in the peptide chain is already possible by attachment of electrons at ~0 eV.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2014