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Updated: Jul 11, 2026

Photoelectron Imaging of Anions Illustrated by 310 Nm Detachment of F−
Published on: July 27, 2018
Ion activation in electron capture dissociation to distinguish between N-terminal and C-terminal product ions
Yury O Tsybin1, Huan He, Mark R Emmett
1Biomolecular Mass Spectrometry Laboratory, Swiss Federal Institute of Technology in Lausanne, Lausanne, CH-1015, Switzerland. yury.tsybin@epfl.ch
Abstract:
We present a method to distinguish N-terminal from C-terminal product ions in electron capture dissociation (ECD) MS/MS due to the change in relative abundances of even-electron (prime) and odd-electron (radical) product ions produced in consecutive ECD and activated ion-ECD mass spectra. The method is based on the rate and direction of hydrogen atom transfer between N-terminal and C-terminal ECD products and its dependence on ion internal energy. We demonstrate that increasing ion internal energy by vibrational activation prior to ECD results in decreased ratio of radical/prime N-terminal product ions (c*/c' ratio), but increased ratio of radical/prime C-terminal product ions (z*/z' ratio) in many cases. The combination of AI-ECD and ECD promises to increase the confidence of mass spectrometry-based peptide sequencing and protein identification.
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