8 Ultrafast Ionization and Fragmentation: From Small Molecules
197
Fig. 8.16 [5] Fs-LID MS/MS spectrum for GAILAGAILR
Fig. 8.17 [5] Fs-LID MS/MS spectrum for GAILMGAILR
The diagnostic side chain losses observed in fs-LID spectra of 12 synthetic peptides have been tabulated in Table 8.3 and are consistent with those reported in the
literature [77, 78, 95]. Note that the neutral loss of even-electron species leaves a
radical on the doubly charged peptide backbone, and can give rise to sequence ions,
meaning that many of the side chain losses observed in fs-LID are intermediate
rather than “dead-end” product ions. This opens the door for sequential dissociation, and also provides radical intermediates that can be isolated and subjected to
MS 3 (or MS n ) for further analysis when present in sufficient abundance. The side
chain losses from I, L, M, and R can be seen in the fs-LID spectra as noted in
Figs. 8.15–8.17.
197
Fig. 8.16 [5] Fs-LID MS/MS spectrum for GAILAGAILR
Fig. 8.17 [5] Fs-LID MS/MS spectrum for GAILMGAILR
The diagnostic side chain losses observed in fs-LID spectra of 12 synthetic peptides have been tabulated in Table 8.3 and are consistent with those reported in the
literature [77, 78, 95]. Note that the neutral loss of even-electron species leaves a
radical on the doubly charged peptide backbone, and can give rise to sequence ions,
meaning that many of the side chain losses observed in fs-LID are intermediate
rather than “dead-end” product ions. This opens the door for sequential dissociation, and also provides radical intermediates that can be isolated and subjected to
MS 3 (or MS n ) for further analysis when present in sufficient abundance. The side
chain losses from I, L, M, and R can be seen in the fs-LID spectra as noted in
Figs. 8.15–8.17.