Development of Charge Transfer Dissociation Mass Spectrometry (CTD-MS) of Oligosaccharides

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With support from the Chemical Measurement and Imaging Program in the Division of Chemistry, Professor Glen Jackson and his group at West Virginia University are developing instruments for the characterization of oligosaccharides - complex sugar molecules critical to living systems. Specifically, Dr. Jackson is assessing and expanding the usefulness of mass spectrometry as a means of determining the structure of these complex biomolecules. The research benefits from collaboration and student exchanges with a research team at the French National Institute for Agricultural Research (INRA) in Nantes, France. The tools being developed help answer important questions about the structure and function of biological molecules including, but not limited to, oligosaccharides. The new instruments can address, for example, questions about how sugars are digested, the gelling properties of food-grade pectins, and cell recognition pathways in living systems. The project is also providing a mechanism to educate elementary school students through organization of activity stations at local science fairs.The Jackson group is developing two mass spectrometers, a 2D and a 3D ion trap, for charge transfer dissociation (CTD) of oligosaccharides. Initial efforts seek to improve fragmentation efficiency by incorporating additional ion optics in the reactant ion beam. This modification may also reduce reaction times, enabling CTD to be coupled with ultra-high performance liquid chromatographic separations of complex mixtures. Instrument variables such as reagent ion kinetic energy, flux, and electron affinity (through the choice of noble gas); CTD reaction time; and the trapping parameter (qz) are optimized to enhance fragmentation behavior. Key aims are the elucidation of general rules for fragmentation and identification of the best conditions with which to augment oligosaccharide characterization. Isolated fractions of well-characterized oligosaccharides are used to elucidate the effect of oligosaccharide properties on the extent and nature of fragmentation. Properties expected to influence glycosidic and cross-ring fragmentation mechanisms include: glycan sequence, inter-residue linkage position, branching point, charge state, adducting ions, and glycan modifications such as esterification, amination and sulfation. Additional studies investigate the efficacy of CTD towards other oxygenated oligomers, including polymers, PEGylated drugs, anionic surfactants and oligonucleotides. These combined studies demonstrate the strengths and weaknesses of CTD relative to existing technologies and help guide future research towards high-impact applications.