Coulomb-assisted dissociative electron attachment: application to a model peptide
Monika Sobczyk1, Iwona Anusiewicz, Joanna Berdys-Kochanska
1Chemistry Department and Henry Eyring Center for Theoretical Chemistry, University of Utah, Salt Lake City, Utah 84112, USA.
The Journal of Physical Chemistry. A
|July 15, 2006
Summary
Electron capture dissociation (ECD) of peptides fragments specific bonds. This study finds that electron attachment to carbonyl pi orbitals, followed by nitrogen-to-alpha-carbon bond cleavage, is the most common fragmentation pathway in ECD experiments.
Area of Science:
- Chemical Physics
- Analytical Chemistry
- Computational Chemistry
Background:
- Peptide fragmentation via electron capture dissociation (ECD) aids in determining primary structures.
- ECD fragmentation preferentially cleaves specific bonds, a phenomenon attributed to stabilizing Coulomb potentials from positive charges.
Purpose of the Study:
- To investigate the stabilizing effects of Coulomb potentials on bond cleavage in a model peptide.
- To elucidate the mechanisms of direct and indirect electron attachment leading to fragmentation in ECD.
Main Methods:
- Utilized ab initio computational methods to examine electron attachment to various bond types in a model peptide.
- Analyzed direct electron attachment to sigma orbitals and indirect attachment to carbonyl pi orbitals.
Main Results:
- Direct electron attachment and sigma bond cleavage were found unlikely, except in highly charged peptides.
- Indirect attachment to a carbonyl C=O pi orbital followed by nitrogen-to-alpha-carbon bond cleavage was identified as the most probable fragmentation pathway.
Conclusions:
- The study provides insight into the ECD mechanism, particularly the favored nitrogen-to-alpha-carbon bond cleavage.
- Results suggest a method to predict susceptible bonds for low-energy electron attachment based on Coulomb energy.
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