Our current FT-ICR research involves gas-phase reactions and dissociation of multiply protonated peptide and protein ions produced by ESI. Because FT-ICR is a trapping form of mass spectrometry, gas-phase biomolecular ions can be allowed to react with neutral molecules for timescales on the orders of milliseconds to minutes. Typical reactions involve deprotonation and hydrogen/deuterium exchange. Using on- and off-resonance frequency irradiation techniques, ions can also be caused to undergo collision-induced dissociation (CID). The high resolution, exact mass measurement capabilities of FT-ICR faciliate assignments of charge and formula for MS/MS product ions. These experiments provide structural, kinetic, and thermodynamic information. We study how amino acid composition and sequence affects reactivity and dissociation. Molecular dynamics calculations are also performed to gain information on the three-dimensional conformations of the ions. Our gas-phase ion chemistry work on compounds of known structures provides information that can be used by researchers working with unknown biomolecules.
The FT-ICR is shown below. It is too big to fit in one picture. Missing from the picture are the Silicon Graphics computer, the data acquisition console, the electronics cabinet, and various rough pumps.
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