title: Electron capture and transfer dissociation: Peptide structure analysis at different ion internal energy levels.
abstract: 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.
authors.affiliation: Biomolecular Mass Spectrometry Laboratory, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
authors.forename: Hisham
authors.initials: H
authors.lastname: Ben Hamidane
authors.forename: Diego
authors.initials: D
authors.lastname: Chiappe
authors.forename: Ralf
authors.initials: R
authors.lastname: Hartmer
authors.forename: Aleksey
authors.initials: A
authors.lastname: Vorobyev
authors.forename: Marc
authors.initials: M
authors.lastname: Moniatte
authors.forename: Yury O
authors.initials: YO
authors.lastname: Tsybin
mesh_terms: D004583:Electrons; D005583:Fourier Analysis; D010455:Peptides / Q000737:chemistry*; D053719:Tandem Mass Spectrometry
chemical_list: D010455:Peptides