title: Ion activation in electron capture dissociation to distinguish between N-terminal and C-terminal product ions.
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.
authors.affiliation: Biomolecular Mass Spectrometry Laboratory, Swiss Federal Institute of Technology in Lausanne, Lausanne, CH-1015, Switzerland. yury.tsybin@epfl.ch
authors.forename: Yury O
authors.initials: YO
authors.lastname: Tsybin
authors.forename: Huan
authors.initials: H
authors.lastname: He
authors.forename: Mark R
authors.initials: MR
authors.lastname: Emmett
authors.forename: Christopher L
authors.initials: CL
authors.lastname: Hendrickson
authors.forename: Alan G
authors.initials: AG
authors.lastname: Marshall
mesh_terms: D000595:Amino Acid Sequence; D004583:Electrons; D006859:Hydrogen / Q000737:chemistry; D007477:Ions / Q000737:chemistry; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry*
chemical_list: D007477:Ions; D010455:Peptides; D011506:Proteins; D006859:Hydrogen