STRUCTURE AND SOLUTION PROPERTIES OF TAMARIND-SEED POLYSACCHARIDE
STRUCTURE AND SOLUTION PROPERTIES OF TAMARIND-SEED POLYSACCHARIDE
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DOI：
10.1016/0008-6215(91)80037-n
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发表时间：
1991-07-30
影响因子：
3.1
通讯作者：
REID, JSG
中科院分区：
文献类型：
--
作者：
GIDLEY, MJ;LILLFORD, PJ;REID, JSG
罗望子种子中的主要多糖是半乳糖基葡聚糖，其半乳糖：木糖：葡萄糖的比例为1：2.25：2.8。少量多糖（2-3%）含有支链（1 -> 5）-α-L-阿拉伯呋喃和非支链（1 -> 4）-β-D-半乳吡喃特征。小角X射线散射实验给出了典型的单链分子的水溶液中的聚合物的横截面半径的值。从静态光散射研究中推断出链的显著刚度（C infinity 110），并部分归因于（1 -> 4）-β-D-葡聚糖主链的运动受到其广泛（约80%）糖基化的限制。聚合物的刚性引起显著的排水效应，这严重影响了流体动力学行为。“零剪切”粘度对浓度的依赖性被用于确定“稀释"和”半稀释“浓度方案。在“半稀释”区域中对浓度的显著依赖性类似于其他刚性中性多糖系统，归因于“超缠结”，并且建议这些可能是通过刚性链的脆弱排列而产生的。
The major polysaccharide in tamarind seed is a galactoxyloglucan for which the ratios galactose:xylose:glucose are 1:2.25:2.8. A minor polysaccharide (2-3%) contains branched (1 --> 5)-alpha-L-arabinofuranan and unbranched (1 --> 4)-beta-D-galactopyranan features. Small-angle X-ray scattering experiments gave values for the cross-sectional radius of the polymer in aqueous solution that were typical of single-stranded molecules. Marked stiffness of the chain (C infinity 110) was deduced from static light-scattering studies and is ascribed partially to the restriction of the motion of the (1 --> 4)-beta-D-glucan backbone by its extensive (approximately 80%) glycosylation. The rigidity of the polymer caused significant draining effects, which heavily influenced the hydrodynamic behaviour. The dependence of ''zero-shear'' viscosity on concentration was used to characterise ''dilute'' and ''semi-dilute'' concentration regimes. The marked dependence on concentration in the ''semi-dilute'' region was similar to that for other stiff neutral polysaccharide systems, ascribed to ''hyper-entanglements'', and it is suggested that these may have arisen through a tenuous alignment of stiffened chains.