NMR spectroscopy, molecular dynamics, and conformation of a synthetic octasaccharide fragment of the O-specific polysaccharide of Shigella dysenteriae type 1

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• 作者：Coxon ; Bruce ; Sari ; Nese ; Batta ; Gyula ; Pozsgay ; Vince
• 关键词：¹³C-Labeling ; Conformation ; NMR spectroscopy ; Octasaccharide ; Restrained molecular dynamics ; Shigella dysenteriae type 1 ; Simulated annealing ; TOCSY ; T-ROESY
• 刊名：Carbohydrate Research
• 出版年：2000
• 出版时间：January 29, 2000
• 年：2000
• 卷：324
• 期：1
• 页码：53-65
• 全文大小：503 K

文摘

A synthetic octasaccharide fragment (2) of the O-specific polysaccharide (1) of Shigella dysenteriae type 1 has been studied as its methyl glycoside by one- and two-dimensional homo- and heteronuclear NMR spectroscopy. Complete ¹H and ¹³C NMR assignments have been generated, and the ¹³C spin–lattice relaxation times have been measured for the octasaccharide 2. A congener (6) of this octasaccharide containing one -galactose residue with a specific ¹³C label at C-1 has been synthesized and used to measure interglycosidic ¹³C–¹H coupling by the 2D J-resolved ¹H NMR method. From the NMR data, three types of conformational restraints were developed: (a) 29 inter-residue, distance restraints; (b) 48 intra-residue, ring atom dihedral angle restraints, and (c) one heteronuclear, inter-residue dihedral angle restraint. The use of these restraints in a restrained molecular dynamics computation with simulated annealing yielded a conformation resembling a short, irregular spiral, with methyl substituents on the exterior.