Macromolecular cyclization of (1-->6)-branched-(1-->3)-beta-D-glucans observed after denaturation-renaturation of the triple-helical structure.
Macromolecular cyclization of (1-->6)-branched-(1-->3)-beta-D-glucans observed after denaturation-renaturation of the triple-helical structure.
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DOI：
10.1002/bip.360330118
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发表时间：
1993
期刊：
影响因子：
2.9
通讯作者：
B. T. Stokke;A. Elgsaeter;D. Brant;T. Kuge;S. Kitamura
中科院分区：
文献类型：
--
作者：
B. T. Stokke;A. Elgsaeter;D. Brant;T. Kuge;S. Kitamura
High molecular weight polysaccharide structure is conventionally described in terms of linear, comb-like, or treelike molecules. At a higher level of organization, various single-and multiple-stranded helical geometries have been described in addition to the less well-defined structures and connectivities that occur in noncovalently cross-linked gels. We report here on the finding of circular morphology in one type of high molecular weight multistranded polysaccharide. Circular structures have been described for synthetic polymers and DNA,'but except for the oligomeric cyclodextrins' and cyclosophoraoses, 3 circular morphology of high molecular weight polysaccharides has not been reported previously.Samples of schizophyllan,'which dissolve as rigid, triple-helical structures in aqueous solution and random coils in dimethylsulfoxide (DMSO),'were subjected to renaturating conditions by dialysis against distilled water of the DMSO solutions. Electron microscopic (EM) observations of heavy metal replicated, vacuum dried specimen^^,^ obtained from the powdered polysaccharide dissolved in aqueous solution revealed almost exclusively linear structures. The limited resolution imposed by the used preparation technique does not allow observations of the side chains in the comb-like schizophyllan structure. Dissolution in DMSO with renaturation by dialysis to aqueous solution at high polymer concentration, ie, c> 4 mg/mL, yielded predominantly aggregated structures, whereas mixtures of circular, linear, and aggregated structures were observed as a result of lowering the polymer concentration to about 1 mg/mL or below during the dialysis procedure. Circular structures were also observed in samples of lentinan. This is a polysaccharide with a chemical structure similar to that of schizophyllan which has received recent attention for its biological activity and which is currently used as a chemostatic agent in cancer therapy. 8
