Ciancia M, Milas M, Rinaudo M
Centre de Recherches sur les Macromolécules Végétales, CERMAV-CNRS, Grenoble, France.
Int J Biol Macromol. 1997 Feb;20(1):35-41. doi: 10.1016/s0141-8130(97)01149-5.
The role of the nature and concentration of counterions and coions on the conformation of kappa-carrageenan is discussed; particularly, that of iodide compared with chloride based on the results obtained from optical rotation, viscometry and microcalorimetry. Iodide gives a more stable helical conformation, with a larger degree of order; at the same time, it represses aggregation of the helices and the gelation ability. Concerning the ordered conformation obtained in the presence of iodide coions, the results obtained are not conclusive. From the enthalpy of the conformational change, it seems that, even in the presence of iodide, the ordered conformation remains a double helix. On the other hand, no doubling of molecular weight was obtained by MALLS/GPC. Thus, this aspect remains still under discussion.
讨论了抗衡离子和同离子的性质及浓度对κ-卡拉胶构象的作用；特别是根据旋光法、粘度测定法和微量量热法所得结果，对比了碘离子与氯离子的作用。碘离子能形成更稳定的螺旋构象，有序程度更高；同时，它抑制螺旋的聚集和凝胶化能力。关于在碘离子同离子存在下获得的有序构象，所得结果尚无定论。从构象变化的焓来看，即使在有碘离子存在的情况下，有序构象似乎仍是双螺旋结构。另一方面，多角度激光光散射/凝胶渗透色谱法（MALLS/GPC）未得到分子量加倍的结果。因此，这方面仍在讨论之中。
