| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 2003: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2002: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Research Abstract |
Sialyl and KDN glycoconjugates are important cell surface components in a variety of intercellular recognitions. Therefore, a study of the conformation and dynamics of those sialyl and KDN oligosaccharides and their analogs may provide a useful insight into how these cell surface oligosaccharide interact with the corresponding receptor molecules. However, although the conformational properties of sialyloligosaccharide analogs of low molecular weight have been reported by many research groups, the conformation and dynamics of sialyloligosaccharides and their analogs attached to glycoproteins have not yet been fully analyzed. To address this problem, ^<13>C-labeled NeuAc has been used for conformational analysis of sialyloligosaccharides on artificial membrane surfaces and TRNOE experiments. It is reportes the novel NMR techniques, that is, HSQC-TOCSY-NOESY-TOCSY, for observation of all protons of NeuAc, H-3 to H-9 even with only a single ^<13>C-atom, at the 3-position of NeuAc, bound to
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a glycoprotein. However, combined multi-pulse techniques generally suffer from low sensitivity. Therefore we have synthesized [3,9-^<13>C]-labeled NeuAc to detect of all protons of NeuAc conveniently by the HMQC-HOHAHA technique. Another goal of the research described herein is to demonstrate the synthetic merits of mixed samples of [3-^<13>C] and [9-^<13>C]NeuAc as opposed to [3,9-^<13>C]NeuAc. This is advantageous because the mixed samples result in higher yields due to the use of excess amounts of the non-labeled substrate. Equal measurements for di-labeled NeuAc and mixed mono-labeled NeuAc by NMR are also demonstrated. This mixed method was developed for the syntheses of effectively labeled disaccharide and Sialyl Le^x mimetic. In these work syntheses of ^<13>C-labeled almost of important component sugar such as KDN, N-Ac-mannosamine, N-Ac-glucosamine, Mannose, Galactose, and Fucose in oligosaccharides were achieved through epoxy intermediates, those are useful for synthesizing modified labeled sugars for further research.
This minimal and efficient labeling method should facilitate studies on the conformational properties and dynamic behavior of oligosaccharides. These labeling methods are also available for ^<14>C derivatives. Less
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