It has been recognized that oligosaccharides, in the form of glycoprotein and glycolipid conjugates, carry detailed structural information that serves to mediate a variety of biological events including inflammation, immunological response and metastasis. While some carbohydrate binding proteins were found to be receptors on the cell surface, their carbohydrate ligands have not yet been determined. Identification of these carbohydrate ligands would be of paramount interest in understanding the involvement of carbohydrates in cell signaling. In order to simplify the very labor-intensive solution-phase synthesis of carbohydrates, considerable efforts have been directed toward the development of strategies and sequences relevant to solid phase synthesis. Recent advances have demonstrated that useful methodologies for glycosidation in solution can be applicable on a polymer support. A major limitation toward the development of new methodologies for solid support synthesis of complex oligosacharides is the difficulty of characterizing the reaction products or intermediates as they are evolving during the course of the synthesis. Until recently, it was necessary to cleave these products from the resin in order to allow for the use of classical spectroscopic means (e.g. solution-state NMR and mass spectrometry) for monitoring the unfolding syntheses. The cleavage method of analysis is time consuming, expensive and wasteful in the context of multistep syntheses. We recently introduced the use of high-resolution magic angle spinning (HR-MAS) NMR for the characterization of polymer bound oligosaccharides. This monitoring method has allowed us to rapidly develop novel methodologies for the assembly of complex glycoconjugates involved in biological processes. Ultimately, these methods may lead to the development of an automated oligosaccharide synthesizer.
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