Fundamental differences in model cell-surface polysaccharides revealed by complementary optical and spectroscopic techniques
Fundamental differences in model cell-surface polysaccharides revealed by complementary optical and spectroscopic techniques
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DOI：
10.1039/c2sm25239b
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发表时间：
2012-01-01
期刊：
影响因子：
3.4
通讯作者：
Weightman, Peter
中科院分区：
文献类型：
--
作者：
Holder, Gareth M.;Bowfield, Andrew;Weightman, Peter
两类多糖，带电的肝素和不带电的葡聚糖作为那些在细胞外基质中发现的模型，形成有序的安排在固体和溶液中的倾向，采用偏振光学显微镜和反射各向异性光谱进行了探讨。固态分子振动的基本模式，这涉及到在环境温度下的构象状态的占有率，也进行了研究，使用太赫兹（1-15太赫兹）光谱在SRS，达雷斯伯里和ANKA，卡尔斯鲁厄的专门建造的光束线。在固态下，通过RAS观察到Na、Ca和Mg离子形式肝素的离子中心各向异性排列的证据，但在100 mg/ml（-1）的水溶液中不存在，并且通过偏振光学显微镜证实溶液中不存在分子有序。带离子电荷的肝素样品显示出非常强的THz辐射吸收，表明这些材料中未占据的较高能量构象状态的可及性，而不带电荷的葡聚糖仅显示出弱的THz吸收，这意味着大多数构象状态被占据，并且这些材料中很少有未占据的较高能量状态。这表明这两类材料将具有非常不同的构象特性，特别是在响应细胞外基质中的温度变化时。
The propensity of two classes of polysaccharides, charged heparins and uncharged dextrans serving as models of those found in the extracellular matrix, to form ordered arrangements in solids and in solution, were explored employing polarising optical microscopy and reflection anisotropy spectroscopy. The fundamental modes of molecular vibration in the solid state, which relate to the occupancy of conformational states at ambient temperatures, were also investigated using terahertz (1-15 THz) spectroscopy on purpose built beam lines at SRS, Daresbury and ANKA, Karlsruhe. In the solid state, evidence for the anisotropic arrangement of ion centres was observed for the Na, Ca and Mg ion forms of heparin by RAS but, this was absent in aqueous solution at 100 mg ml(-1) and the absence of molecular ordering in solution was confirmed by polarised optical microscopy. The ion charged heparin specimens showed very strong absorption of THz radiation indicating the accessibility of unoccupied higher energy conformational states in these materials whereas the uncharged dextrans showed only weak THz absorption, implying that the majority of conformational states are occupied and there are few unoccupied higher energy states in these materials. This suggests the two classes of material will have very different conformational properties, particularly in response to temperature changes in the extracellular matrix.