P V Shchukin1, M V Muftakhov, A V Pogulay. 1. Institute of Molecules and Crystals Physics, Ufa Research Center of Russian Academy of Sciences, Prospekt Oktyabrya 151, 450075, Ufa, Russia. pavel@anrb.ru
Abstract
RATIONALE: Dipeptide molecules are good model systems for investigation of resonant reactions of low-energy electrons with proteins. The present work is devoted to the study of the processes of formation and fragmentation of negative ions in aliphatic dipeptides glycyl-glycine and glycyl-alanine. The metastable decays of negative ions were detected in these objects, and have been investigated with the aim of clarification of the mechanisms of fragmentation. METHODS: The effective yield curves for negative ions as functions of electron energy were obtained using a magnetic sector mass spectrometer rebuilt for generation and detection of negative ions. For analysis of the observed metastable decays statistical and thermochemical approaches have been used. RESULTS: The ions structures, the enthalpies of formation of neutral and charged particles, and the rate constants of dissociative reactions have been found. CONCLUSIONS: Comparison of the experimental results with theoretical data leads to the conclusion that metastable ion decay proceeds with minimal structural changes avoiding complicated rearrangements and isomerization processes.
RATIONALE: Dipeptide molecules are good model systems for investigation of resonant reactions of low-energy electrons with proteins. The present work is devoted to the study of the processes of formation and fragmentation of negative ions in aliphatic dipeptidesglycyl-glycine and glycyl-alanine. The metastable decays of negative ions were detected in these objects, and have been investigated with the aim of clarification of the mechanisms of fragmentation. METHODS: The effective yield curves for negative ions as functions of electron energy were obtained using a magnetic sector mass spectrometer rebuilt for generation and detection of negative ions. For analysis of the observed metastable decays statistical and thermochemical approaches have been used. RESULTS: The ions structures, the enthalpies of formation of neutral and charged particles, and the rate constants of dissociative reactions have been found. CONCLUSIONS: Comparison of the experimental results with theoretical data leads to the conclusion that metastable ion decay proceeds with minimal structural changes avoiding complicated rearrangements and isomerization processes.
Authors: Filipe Ferreira da Silva; Carolina Matias; Diogo Almeida; Gustavo García; Oddur Ingólfsson; Helga Dögg Flosadóttir; Benedikt Ómarsson; Sylwia Ptasinska; Benjamin Puschnigg; Paul Scheier; Paulo Limão-Vieira; Stephan Denifl Journal: J Am Soc Mass Spectrom Date: 2013-09-17 Impact factor: 3.109