Eur. Phys. J. D (2014) 68: 119
https://doi.org/10.1140/epjd/e2014-40815-2

Regular Article

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 Innsbruck, Austria

^a e-mail: stephan.denifl@uibk.ac.at

Received: 19 December 2013
Received in final form: 7 March 2014
Published online: 9 May 2014

Abstract

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-C_α bond in the peptide chain is already possible by attachment of electrons at ~0 eV.