Organisation and association of kappa-carrageenan helices under different salt conditions
Organisation and association of kappa-carrageenan helices under different salt conditions
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DOI：
10.1016/s0141-8130(97)00054-8
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发表时间：
1997-08-01
影响因子：
8.2
通讯作者：
Viebke, C
中科院分区：
文献类型：
--
作者：
Piculell, L;Borgstrom, J;Viebke, C
添加盐 NaI 和 CsI 的混合物可用于逐渐“调节”κ-卡拉胶 (KC) 螺旋在溶液中聚集的倾向。我们表明，这种方法可用于解决在某些条件下螺旋形成导致凝胶化的分子事件。我们还概述了当 NaI/CsI 比率和 KC 浓度变化时，螺旋 KC（未降解或超声降解）出现的各种聚集和组织状态。在明确定义的铯部分上方发现了向刚性超螺旋棒的过渡。这种转变反映在一系列实验测量中，例如低温透射电子显微镜、旋光度、粘度测量和小变形振荡测量。超螺旋杆状态似乎对于 KC 与刺槐豆胶的结合也很重要，并且刺槐豆胶被发现可以稳定这种状态。当铯含量低于转变阈值时，仅发现了 KC 的新态。未降解的 KC 在足够高的浓度 (> ca, 1%) 下形成弱凝胶。相比之下，超声降解的 KC 在这些盐条件下以足够高的浓度 (> 约 5%) 形成手性向列液晶相。 (C) 1997 Elsevier Science B.V.
Mixtures of the added salts NaI and CsI can be used to gradually 'tune' the propensity of kappa-carrageenan (KC) helices to aggregate in solution. We show that this method can be used to resolve the molecular events by which helix formation, under certain conditions, leads to gelation. We also present an overview of the various states of aggregation and organisation that appear for helical KC (non-degraded or ultrasonically degraded) when the NaI/CsI ratio and the concentration of KC are varied. A transition to rigid, superhelical rods is found above a well-defined fraction of cesium. This transition is reflected in a range of experimental measurements, such as cryo-transmission electron microscopy, optical rotation, viscometry and small deformation oscillatory measurements. The superhelical-rod state also seems essential for the association of KC with locust bean gum, and locust bean gum is found to stabilise this state. Novel states of KC alone have been found at cesium contents below the transition threshold. Non-degraded KC forms weak gels at sufficiently high concentrations (> ca, 1%). In contrast, ultrasonically degraded KC forms a chiral nematic liquid crystalline phase at sufficiently high concentrations (> ca. 5%) under these salt conditions. (C) 1997 Elsevier Science B.V.