CONFORMATION AND INTERMOLECULAR INTERACTIONS OF CARBOHYDRATE CHAINS
CONFORMATION AND INTERMOLECULAR INTERACTIONS OF CARBOHYDRATE CHAINS
复制标题
DOI：
10.1002/jss.400060211
复制
发表时间：
1977-01-01
期刊：
影响因子：
--
通讯作者：
WELSH, EJ
中科院分区：
文献类型：
--
作者：
MORRIS, ER;REES, DA;WELSH, EJ
考虑到它们的构象和相互作用，碳水化合物链可以根据它们的共价结构方便地分为3类；即，周期(a)，中断周期(b)和非周期(c)类型。在水溶液中，碳水化合物链常以高度无序的无规线圈形式存在。在适当的条件下，(a)和(b)型多糖可以采用多种有序构象。物理方法，特别是旋光性、圆二色性和核磁共振，为研究水溶液中这些无序-有序转变的机理和特异性提供了灵敏的探针。这种多糖链之间的分子间相互作用是由采用有序构象的长结构规则区域的合作结合而产生的。对于酸性多糖，这些合作关系可能包括在它们之间夹有阳离子的延伸带的排列。在其他系统中，相互作用涉及双螺旋，然后可能进一步聚集，并且不同多糖链的几何匹配也可能发生。这些有序的、相关的区域通常由于偏离结构规则或由于阻止分子完全聚集的扭结而终止。发生在动物细胞外围的复杂碳水化合物链具有非常不同的非周期性结构，尽管它们的构象尚不清楚，但已考虑到初步迹象。
For consideration of their conformations and interactions, carbohydrate chains can conveniently be divided into 3 classes on the basis of their covalent structure; i.e., periodic (a), interrupted periodic (b) and aperiodic (c) types. In aqueous solution carbohydrate chains often exist as highly disordered random coils. Under appropriate conditions, polysaccharides of types (a) and (b) can adopt a variety of ordered conformations. Physical methods, and in particular optical rotation, circular dichroism and NMR, provide sensitive probes for the study of the mechanism and specificity of these disorder-order transitions in aqueous solution. Intermolecular interactions between such polysaccharide chains arise from cooperative associations of long structurally regular regions which adopt the ordered conformations. For acidic polysaccharides these cooperative associations may involve alignment of extended ribbons with cations sandwiched between them. In other systems the interactions involve double helices which may then aggregate further, and geometric matching of different polysaccharide chains can also occur. These ordered, associated regions are generally terminated by deviations from structural regularity or by kinks which prevent complete aggregation of the molecules. The complex carbohydrate chains which occur at the periphery of animal cells have very different, aperiodic structures and although their conformations are as yet poorly understood, preliminary indications are considered.