Česká společnost pro hmotnostní spektrometrii

(1. konference České společnosti pro hmotnostní spektrometrii - PL-2)
Peptide cation radicals by electron-ion recombination

František Tureček ^1 *, Thomas W. Chung ¹, Christopher L. Moss ¹

1. University of Washington

Abstrakt

Electron-ion recombination triggers extensive dissociations of peptide ions that provide valuable sequence information. The main dissociations are cleavage of backbone N---C-alpha bonds and side-chain losses. Our main interest in this area has been in elucidating the energetics and mechanisms of peptide electron-based dissociations that are observed in electron capture dissociation (ECD) and electron transfer dissociation (ETD) mass spectrometry [1]. Experimental methods included modifying the peptide with spin-trapping and fixed-charge groups [2], charge-reversal [3], ion mobility, and IRMPD using a free electron laser. Computational analysis involved conformational search, cation-radical structures, transition states, RRKM kinetics, and quantum Ehrenfest dynamics. Another area of interest concerns dissociations of primary ETD fragments with the goal of extracting additional sequence information. For example, primary z ions from arginine-containing peptides undergo backbone dissociations that depend on the nature of the amino acid residues in the peptide. Residues that engage in radical hydrogen transfers can promote or block backbone dissociations, depending on the nature of the residue. Radical- trapping residues such as cysteine and methionine effectively quench backbone dissociations. The energetics and kinetics of backbone dissociations will be discussed. In addition, newest results of quantum Ehrenfest dynamics will be presented to document the role of excited electronic states in peptide cation-radical dissociations.

* Korespondující autor: turecek@chem.washington.edu

Literatura

1. Syrstad E.A. and Tureček F. J.: Am. Soc. Mass Spectrom. 16, 208-224 (2005).
2. Chung T.W. et al.: J. Am. Soc. Mass Spectrom. 22, 13-30 (2011).
3. Tureček F. et al.: J. Am. Chem. Soc. 131, 16472-16487 (2009).