Laser-induced dissociation of singly protonated peptides at 193 and 266 nm within a hybrid linear ion trap mass spectrometer

• Published in: Rapid communications in mass spectrometry Vol. 27; no. 10; pp. 1119 - 1127
• Main Authors: Lai, Cheuk-Kuen, Ng, Dominic C. M., Pang, H. F., Le Blanc, J. C. Yves, Hager, James W., Fang, De-Cai, Cheung, A. S.-C., Chu, Ivan K.
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 30.05.2013
• Subjects: Amino Acid Sequence; Angiotensins - chemistry; Bradykinin - chemistry; Enkephalins - chemistry; Lasers; Mass Spectrometry - methods; Peptide Fragments - chemistry; Peptides - chemistry; Protons
• ISSN: 0951-4198; 1097-0231
• DOI: 10.1002/rcm.6545

RATIONALE 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. Copyright © 2013 John Wiley & Sons, Ltd.