Synthesis and Analytical Evaluation of New Oligosaccharide Tags
Annual Conference of the Society for Glycobiology
Society for Glycobiology
November 9-12, 2005
Date of Presentation
Carbohydrates play vital roles in numerous biological processes. Separation and structural elucidation of carbohydrate oligomers is crucial for meaningful structure-activity studies. The structural elucidation of constituent glycans by techniques similar to those used in proteomics is still at a nascent stage. The analysis of biologically important oligosaccharides is complicated by structural complexity (stereochemistry, linkage, and anomericity), poor detectability in chromatography and minute amounts (Harvey, 1996). Currently, the lack of chromophores in native carbohydrates is typically addressed by introducing fluorescent or chromophoric tags to improve detectability during chromatographic separation. The labeling is most commonly done by reductive amination of the aldehyde in the presence of sodium cyanoborohydride (Hase, 1996). Whereas low-molecular mass carbohydrates can be labeled very efficiently in this manner, high-molecular mass oligosaccharides often suffer from reduced labeling efficiency presumably because of steric reasons. In our previous studies, a biotinylated tag with a benzene core was successfully synthesized and introduced into different oligosaccharides. This tag combines bioaffinity for purification and UV activity for photo-diode array detection in HPLC. Also, the tag can be deuterium coded through reductive amination in the presence of NaCNBD3, and the carbohydrate derivative can be N-quaternized for electrophoretic applications. To increase the UV detectability, we synthesized a variety of tags with substituents at the benzene core. In this poster, we present the synthesis of new multifunctional biotinylated tags with m-xylylenediamine, 4-nitroanisole, 4-methoxybenzonitrile, and 4 methoxybenzamide. Examples for reductive amination of oligosaccharides with the new tags, HPLC separation, and detection of the derivatives by MALDI-TOF and ESI mass spectrometry will be discussed. We also investigated click chemistry (1,3-dipolar Huisgen cycloaddition) as an alternative approach to reductive amination (Kolb and Sharpless, 2003; Kuijpers et al., 2004). We demonstrated that the tag with a pendent alkyne group could be successfully clicked to benzylazide to give the 1,2,3-triazole in high yield under very mild conditions. We are currently perusing the introduction of an alkyne group into the tags for reaction with sugar azides. The results of these studies will be presented.
Chindarkar, N. S.,
Franz, A. H.
Synthesis and Analytical Evaluation of New Oligosaccharide Tags.
Paper presented at Annual Conference of the Society for Glycobiology in Boston, MA.
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