Electron capture and transfer dissociation: Peptide structure analysis at different ion internal energy levels.
We decoupled electron-transfer dissociation (ETD) and collision-induced dissociation of charge-reduced species (CRCID) events to probe the lifetimes of intermediate radical species in ETD-based ion trap tandem mass spectrometry of peptides. Short-lived intermediates formed upon electron transfer require less energy for product ion formation and appear in regular ETD mass spectra, whereas long-lived intermediates require additional vibrational energy and yield product ions as a function of CRCID amplitude. The observed dependencies complement the results obtained by double-resonance electron-capture dissociation (ECD) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and ECD in a cryogenic ICR trap. Compared with ECD FT-ICR MS, ion trap MS offers lower precursor ion internal energy conditions, leading to more abundant charge-reduced radical intermediates and larger variation of product ion abundance as a function of vibrational post-activation amplitude. In many cases decoupled CRCID after ETD exhibits abundant radical c-type and even-electron z-type ions, in striking contrast to predominantly even-electron c-type and radical z-type ions in ECD FT-ICR MS and especially activated ion-ECD, thus providing a new insight into the fundamentals of ECD/ETD.
Ben Hamidane
Hisham
H
Biomolecular Mass Spectrometry Laboratory, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
Chiappe
Diego
D
Hartmer
Ralf
R
Vorobyev
Aleksey
A
Moniatte
Marc
M
Tsybin
Yury O
YO
D004583:Electrons; D005583:Fourier Analysis; D010455:Peptides / Q000737:chemistry*; D053719:Tandem Mass Spectrometry
D010455:Peptides