Grazing incidence surface-induced dissociation of protonated peptides generated by matrix-assisted laser desorption/ionization

The grazing incidence surface-induced dissociation (GI-SID) of various prot onated peptides with typical kinetic energies of 350 eV was investigated. P eptide ions were generated by matrix-assisted laser desorption/ionization ( MALDI) using delayed extraction. The collision target surfaces used were al uminum and a liquid film of perfluorinated hydrocarbons. All peptides studi ed in these experiments showed enhanced fragment ion yields at grazing inci dence (GI-SID effect) as observed in our former experiments with other prec ursor ion types, In general the GI-SID spectra exhibit N-terminal a(1)-type fragment ions, immonium ions and side-chain fragment ions in the low mass- to-charge region. Fragment ion series of the peptide backbone were not obse rved, which are typical and abundant in the spectra of established fragment ation techniques like collision-induced dissociation, MALDI post-source dec ay or surface-induced dissociation at steeper angles. The potential of the GI-SID process to yield useful information for primary structure determinat ion of peptides is indicated by the observed differences in the GI-SID spec tra of the isomeric dipeptides LR and IR. Copyright (C) 2000 John Wiley & S ons, Ltd.