Surface-induced dissociation of ions produced by matrix-assisted laser desorption/ionization in a fourier transform ion cyclotron resonance mass spectrometer.

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