Intermediate pressure matrix-assisted
laser desorption/ionization (MALDI) source was constructed and interfaced with a 6-T Fourier transform ion
cyclotron resonance mass spectrometer (FT-ICR MS) specially configured for surface-induced dissociation (
SID) studies. First MALDI-
SID results in FT-ICR are presented, demonstrating unique advantages of
SID over conventional FT-ICR MS ion activation techniques for structural characterization of singly protonated
peptide ions. Specifically, we demonstrate that
SID on a
diamond surface results in a significantly better sequence coverage for singly protonated
peptides than SORI-CID. A combination of two effects contributes to the improved sequence coverage: shattering of
peptide ions on surfaces opens up a variety of dissociation channels at collision energies above 40 eV, and second, wide internal energy distribution deposited by collision with a stiff
diamond surface provides an efficient mixing between the primary reaction channels that are dominant at low internal energies and extensive fragmentation at high internal excitation that results from shattering. Activation of MALDI-generated
ions by collisions with surfaces in FT-ICR MS is a new powerful method for characterization and identification of biomolecules