SOLID-STATE AND SOLUTION CONFORMATION OF SCLEROGLUCAN
SOLID-STATE AND SOLUTION CONFORMATION OF SCLEROGLUCAN
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DOI：
10.1016/s0008-6215(00)81030-7
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发表时间：
1982-01-01
影响因子：
3.1
通讯作者：
RINAUDO, M
中科院分区：
文献类型：
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作者：
BLUHM, TL;DESLANDES, Y;RINAUDO, M
核盘菌葡聚糖是一种中性多糖，由(1.fwdarw.3)-β-D-吡喃葡萄糖基残基与(1.fwdarw.6)连接在每3个残基上的β-D-吡喃葡萄糖基。研究了核葡聚糖在溶液和固体中的构象行为。通过测量特性粘度，研究了水溶液中的有序-无序转变。结果表明，在pH=12时发生这种转变，而在10℃时形成凝胶。是观察到的。在取向纤维上进行的X射线衍射实验表明，主链构象与先前观察到的Curdlan相似，即三螺旋。挂件(1.fwdarw.6)连接的β-D-吡喃葡糖残基从三链体的外部突出，导致晶胞基面参数的扩展，并进一步阻碍了硬葡聚糖链的侧向堆积。通过分子模拟的构象分析，可以使观察到的行为合理化。至于龙胆二糖残基，(1.fwdarw.)6)-β-连接被公开。这种构象自由在围绕(1.fwdarw)的旋转中没有显著改变。6)-β-核葡聚糖重复单元中的连锁。结合溶液和固态研究，可以深入了解核葡聚糖的水凝胶形成特性。
Scleroglucan [a Sclerotinia constituent] is a neutral polysaccharide composed of a linear chain of (1 .fwdarw. 3)-linked .beta.-D-glucopyranosyl residues with (1 .fwdarw. 6)-linked .beta.-D-glucopyranosyl groups attached to every 3rd residue. The conformational behavior of scleroglucan was investigated in solution and in the solid state. Order-disorder transitions in aqueous solution were studied by measurement of intrinsic viscosity. The results indicate the occurrence of such a transition at a pH > 12, whereas gel formation under 10.degree. is observed. X-Ray diffraction experiments performed on oriented fibers indicate that the backbone conformation is similar to that previously observed for curdlan, i.e., a triple helix. The pendent (1 .fwdarw. 6)-linked .beta.-D-glucopyranosyl residues protrude from the outside of the triplex, causing an expansion of the base plane parameters of the unit cell and further hampering lateral packing of the scleroglucan chains. The observed behavior can be rationalized on the basis of a conformational analysis involving molecular modelling. As for the gentiobiose residue, extreme conformational flexibility about the (1 .fwdarw. 6)-.beta.-linkage is disclosed. This conformational freedom is not significantly altered for the rotations about the (1 .fwdarw. 6)-.beta.-linkage in the scleroglucan repeating-unit. Combination of solution and solid-state investigations provides insight into the aqueous gel-forming characteristics of scleroglucan.