34 NMRを用いた分子レベルでの分子間認識機構研究(口頭発表の部)
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概要
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A great many host-parasite and host-pathogen interactions depend upon specific oligosaccharide-protein interactions, and the techniques which we have developed are ideally suited for detailed studies on the molecular basis of such interactions. Systems in which we have a particular interest are the carbohydrate-binding A-B class bacterial toxins such as cholera toxin and the toxin derived from E. coli O157. A novel development concerns the use of oligosaccharide ligands which have been enriched with stable isotopes, in order to delineate their bound-state conformations in the absence of detailed structural information on the protein, using isotope edited NMR. This approach involves the chemical synthesis of oligosaccharides which are variously enriched at certain atomic positions, using commercially available isotopically enriched monosaccharides as starting materials. In fact, this synthesis stage plays the most important role. An added bonus is that additional NMR parameters become available as a result of isotopic enrichment, which can be utilised to define more accurately the solution behaviour of the oligosaccharide in the 'free' state, which greatly assists our understanding of the thermodynamics of the oligosaccharide-protein interaction. In our research of VTB (B Subunit of Verotoxin-1) with a ligand, Gb_3 trisaccharide, we successfully obtained several TRNOEs which indicated Gb_3 trisaccharide occupied onto Site2 although Sitel was thought as the primary binding site. Measurement of dipolar couplings by liquid crystal NMR confirmed strongly our result. We have, now, applied these methods for other host-guest systems (it may weaker than VTB-Gb_3 system) and applied liquid crystalline phase NMR for assay of libraries.
- 天然有機化合物討論会の論文
- 2002-09-01