title: Laser-induced dissociation of singly protonated peptides at 193 and 266 nm within a hybrid linear ion trap mass spectrometer.
abstract: BACKGROUND
  We implemented, for the first time, laser-induced dissociation (LID) within a modified hybrid linear ion trap mass spectrometer, QTrap, while preserving the original scanning capabilities and routine performance of the instrument.
  
  
  METHODS
  Precursor ions of interest were mass-selected in the first quadrupole (Q1), trapped in the radiofrequency-only quadrupole (q2), photodissociated under irradiation with a 193- or 266-nm laser beam in the third quadrupole (q3), and mass-analyzed using the linear ion trap.
  
  
  RESULTS
  LID of singly charged protonated peptides revealed, in addition to conventional amide-bond cleavages, preferential fragmentation at Cα -C/N-Cα bonds of the backbone as well as at the Cα -Cβ /Cβ -Cγ bonds of the side-chains. The LID spectra of [M+H](+) featured product ions that were very similar to the observed radical-induced fragmentations in the CID spectra of analogous odd-electron radical cations generated through dissociative electron-transfer in metal-ligand-peptide complexes or through laser photolysis of iodopeptides.
  
  
  CONCLUSIONS
  LID of [M+H](+) ions results in fragmentation channels that are comparable with those observed upon the CID of M(•+) ions, with a range of fascinating radical-induced fragmentations.
authors.affiliation: Department of Chemistry, The University of Hong Kong, Hong Kong, China.
authors.forename: Cheuk-Kuen
authors.initials: CK
authors.lastname: Lai
authors.forename: Dominic C M
authors.initials: DC
authors.lastname: Ng
authors.forename: H F
authors.initials: HF
authors.lastname: Pang
authors.forename: J C Yves
authors.initials: JC
authors.lastname: Le Blanc
authors.forename: James W
authors.initials: JW
authors.lastname: Hager
authors.forename: De-Cai
authors.initials: DC
authors.lastname: Fang
authors.forename: A S-C
authors.initials: AS
authors.lastname: Cheung
authors.forename: Ivan K
authors.initials: IK
authors.lastname: Chu
mesh_terms: D000595:Amino Acid Sequence; D000809:Angiotensins / Q000737:chemistry; D001920:Bradykinin / Q000737:chemistry; D004745:Enkephalins / Q000737:chemistry; D007834:Lasers; D013058:Mass Spectrometry / Q000379:methods*; D010446:Peptide Fragments / Q000737:chemistry; D010455:Peptides / Q000737:chemistry*; D011522:Protons
chemical_list: D000809:Angiotensins; D004745:Enkephalins; D010446:Peptide Fragments; D010455:Peptides; D011522:Protons; D001920:Bradykinin