120th General Meeting of the KCS

Type Poster Presentation
Area Physical Chemistry
Room No. Exhibition Hall 2+3
Time 10월 20일 (금요일) 13:00~14:30
Code PHYS.P-122
Subject Infrared multiphoton dissociation of a-type peptide ion derived from triglycine by experiment and theory
Authors Seungtaek Rim, Jongcheol Seo1, Seung Koo Shin*
Department of Chemistry, Pohang University of Science and Technology, Korea
1Department of Molecular Physics, Fritz Haber Institute of the Max Planck Society, Germany
Abstract Peptide ions isomerize while undergoing fragmentation in the gas phase. To address this issue, we studied the unimolecular dissociation of the a-type ion derived from protonated triglycine. We calculated the microcanonical rate constant for every step of isomerization using the RRKM theory based on ab initio potential energy surface. We also obtained the infrared multiphoton dissociation (IRMPD) spectra of the a-type ion by experiment. The overall reaction rate is numerically simulated to examine the temporal variation of the isomers of the a-type ion prior to dissociation as a function of internal energy. Comparison of the calculated infrared spectra with experiment suggests that resulting infrared spectra are determined by the population of the transient isomeric species. Thus, the infrared spectra of peptide ion result from the reaction intermediates involved in unimolecular dissociation rather than the reactant ion.
E-mail rseungt@postech.ac.kr