title: Charge location directs electron capture dissociation of peptide dications.
abstract: The effect of peptide dication charge location on electron capture dissociation (ECD) fragmentation pattern is investigated. ECD fragmentation patterns are compared for peptides with amide and free acid C-terminal groups. ECD of free acid compared with C-terminally amidated peptides with basic residues near the N-terminus demonstrates increased formation of a-type ions. Similarly, ECD of free acid compared with C-terminally amidated peptides with basic residues near the C-terminus exhibits increased formation of y-type ions. Alteration of the peptide sequence to inhibit the formation of charged side chains (i.e., amino acid substitution and acetylation) provides further evidence for charge location effect on ECD. We propose that formation of zwitterionic peptide structures increases the likelihood of amide nitrogen protonation (versus basic side chains), which is responsible for the increase in a- and y-type ion formation.
authors.affiliation: Ion Cyclotron Resonance Program, National High Magnetic Field Laboratory Florida State University, Tallahassee, Florida 32310-4005, USA.
authors.forename: Yury O
authors.initials: YO
authors.lastname: Tsybin
authors.forename: Kim F
authors.initials: KF
authors.lastname: Haselmann
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: D000465:Algorithms; D002412:Cations; D041961:Deuterium Exchange Measurement / Q000379:methods*; D004583:Electrons; D013058:Mass Spectrometry / Q000379:methods*; D008956:Models, Chemical; D008958:Models, Molecular; D010455:Peptides / Q000032:analysis* / Q000737:chemistry*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012984:Software; D055672:Static Electricity
chemical_list: D002412:Cations; D010455:Peptides