MASS SPECTROMETRY OF METAL COORDINATED OLIGOSACCHARIDES

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The long term goal of this project includes the development of analytical methodology for sequencing and determining linkage position of underivatized oligosaccharides which are coordinated to various metals. Delineation of gas phase mechanisms and fragmentation pathways of these oligosaccharides, which is equally important, will be investigated using Tandem Mass Spectrometry (MS/MS, and MS/MS/MS). Semiempirical calculations will also be utilized as a tool for predicting gas phase conformation of these metal-coordinated compounds. Fast atom bombardment ionization in combination with tandem mass spectrometry of lithium- coordinated oligosaccharides has already been used to unambiguously differentiate the linkage position of isomeric di-, tri-, and tetrasaccharides of the glucose moiety. Extensions of this method to branched glucose and glucosamine oligomers, glycolipids and cerebrosides will be undertaken as well as extending the mass range of analysis to 3,000 Dalton. Tandem mass spectrometry of the multi-lithiated oligosaccharides will be investigated as well as probing the coordination chemistry of several other metals (Mg, Ca, V, Mn, Fe, Co, Cu, Ag, Zn) to these sugars. Extensive labeling studies will be carried out to probe the chemistry of dissociation of these oligomers. Semiempirical calculations of the oxygen-linked and carbon-linked oligosaccharides will provide information which will allow us to determine the most likely site(s) of metal coordination.