3 理論計算に基づいたオリゴ糖の新規合成法の開発と立体配座解析(口頭発表の部)

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The elicitor active hexa-β-D-glucopyranosyl-D-glucitol (1), isolated from mycelial wall of Phytophthora megasperma f. sp. glycinea, stimulates the formation of antibiotic phytoalexins in soybean. Our interest associated with (1) is to elucidate the conformational differences between the elicitor active and elicitor inactive saccharides. As the oligosaccharide (1) is composed of two repeating segments 2, we plan to examine the synthesis and conformational analysis of the trisaccharide 2. Here we report a new synthetic approach of a branched oligosaccharide such as the trisaccharide 2 by spacer mediated glycosilation, and the conformational analysis of the trisaccharide 2 in water based on molecular mechanics calculations. Spacer mediated glycosilation was performed on trisaccharide 5 and 6. The regioselectivity in the intramolecular glycosilation was predicted based on AMBER calculations. These calculations suggested that the reaction of 5 and 6 should result in regioselective glycosilation at 4-position of the glycosyl acceptor. The experimental result indicated that the glycosilation was carried out to afford 4-O-glycoside 18, which could not be obtained in intermolecular glycosilation of 20 with 21. The conformational details of oligosaccharides are essential for understanding the process of chemical binding at receptor site. Thus we performed the conformational analysis of the trisaccharide 2 in water based on MM2, AMBER (United Atom), AMBER (All Atom) programs and NMR spectra. The conformation of 2 obtained from NOESY spectrum data in D_2O showed good agreement with the conformation obtained from AMBER (United Atom) program with solvation. These results indicate that we have developed a protocol for full confomational search of oligosaccharide in water based on GB/SA solvation model.
天然有機化合物討論会の論文
1992-09-10

3 理論計算に基づいたオリゴ糖の新規合成法の開発と立体配座解析(口頭発表の部)

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