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Updated: Jun 19, 2026
13:59
Methods to Identify the NMR Resonances of the 13C-Dimethyl N-terminal Amine on Reductively Methylated Proteins
Published on: December 12, 2013
Resonant electron capture by some amino acids esters.
Yury V Vasil'ev1, Benjamin J Figard, Douglas F Barofsky
1Department of Chemistry, Oregon State University, Corvallis, Oregon 97331.
Journal of the American Chemical Society
|October 20, 2009
Summary
Resonant electron capture reveals new mechanisms for amino acid negative ion formation. Conformational preferences are key for efficient fragmentation of parent negative ions in gas-phase reactions.
Area of Science:
- Physical Chemistry
- Chemical Physics
- Molecular Dynamics
Background:
- Negative ion (NI) formation in amino acids is crucial for understanding their chemical behavior.
- Previous studies linked efficient NI fragmentations to C-termini, but lower energy mechanisms remained unclear.
Purpose of the Study:
- To elucidate novel mechanisms of negative ion formation in amino acids and their esters.
- To investigate the role of conformational preferences in gas-phase fragmentation pathways.
Main Methods:
- Resonant electron capture experiments at low and high temperatures.
- Analysis of negative ion (NI) fragmentations in Glycine, Alanine, and Phenylalanine esters.
- Theoretical investigation of coupling between dipole-bound and valence negative ion states.
Main Results:
- A new mechanism involving coupling between dipole-bound and valence negative ion states was identified for low-energy processes.
- Underivatized amino acids fragment via hydrogen atom tunneling from the bottom adiabatic surface, forming carboxylate anions.
- Amino acid esters fragment through the upper adiabatic state, forming analogues [M-X](-) NIs without barrier penetration.
Conclusions:
- Conformational preferences significantly influence the dissociation of parent negative ions.
- The identified mechanisms provide deeper insights into the fundamental processes of electron capture and fragmentation in amino acids.
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