Synthesis of Tethered Trisaccharides To Probe Inter-Saccharide Flexibility in Carbohydrate−Protein Interactions
作者:Ramon Alibés、David R. Bundle
DOI:10.1021/jo9806097
日期:1998.9.1
Two crystal structures of the trisaccharide epitope alpha-D-Galp(1-->2)[alpha-D-Abep(1-->3)alpha-D-Manp1-->OCH(3) 1 bound to antibody Fab and single-chain Fv fragments have been used to guide the design of an intramolecular tether that constrains the trisaccharide ligand to conformations close to those of the bound state. Preorganization of the ligand should overcome entropic penalties to binding and
三糖表位的两个晶体结构alpha-D-Galp(1-> 2)[alpha-D-Abep(1-> 3)alpha-D-Manp1-> OCH(3)1与抗体Fab和单链Fv片段已用于指导分子内束缚的设计,该束缚将三糖配体约束为接近结合态的构象。配体的预组织应克服对结合的熵罚并提供增强的亲和力。使用三个系链[O(CH(2))(n)()O,n = 6、7和8]固定甘露糖和半乳糖残基的溶剂暴露C6原子。使用了两种合成方案。第一种使用带有被保护为三苯甲基醚6-8的系链的1-硫代半乳糖苷乙基。供体6-8中的任何一个在C6处含有甲磺酸盐的甘露吡喃糖苷5的糖基化得到二糖37-39。随后除去三苯甲基,允许在系链的ω-羟基上生成醇盐,以38%的收率置换磺酸盐。通过比较,当掺入ω-甲磺酰氧基系绳作为甘露糖苷9时,与半乳糖基供体10反应后的二糖产物52以61%的产率转化为大环4。通过硫代糖苷化学法引入3,6-二脱氧