Methods for Isotope Labelling of Glycans

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PROJECT SUMMARY. Glycomics studies are crucial for correlating changes in glycan structure and abundance to the phenotype of a biological system. Among the available platforms to facilitate glycomics analyses, labelling with stable isotopes has been implemented to decipher structural and quantitative aspects of carbohydrates in healthy and diseased states. Isotopically labelled saccharides are also a useful tool for in vivo metabolic profiling and in mechanistic studies in chemistry and enzymology. While some structures are commercially available, a generally applicable and non-destructive method for introducing stable heavy isotopes either in simple monosaccharides or complex oligosaccharides are not available. To overcome these limitations, we will develop a chemical technology based on carbon-13 labelling. To achieve this objective, we will pursue two specific aims: In Aim 1, we will optimize catalytic methods for selective labelling of monosaccharides with carbon-13. This method will selectively exchange the anomeric position with a heavy isotope from readily available sources of carbon-13. In Aim 2, we will apply isotope labelling method to three classes of saccharides of biomedical relevance, namely heparan sulfate proteoglycans, N-linked glycoproteins, and human milk oligosaccharides. Per requirements of PAR-19-254, we will benchmark the new technologies against the current state-of-the-art methods for oligosaccharide quantification. Upon completion of this project, a new catalytic technology for labelling of carbohydrates and glycoconjugates will be available and will complement the current tools for quantitative glycomics. In a broader sense, integration of these novel chemistries with modern mass spectrometry techniques will provide better tools for therapeutic diagnosis.