ABSTRACT:A sample of scleroglucan, a commercially available, water-soluble polysaccharide, and its sonicated fragment were investigated by chemical analysis and by light scattering and viscometry with water containing 0.01 N sodium hydroxide (NaOH), dimethylsulfoxide (DMSO), and water+ DMSO mixtures at 25cC as the solvents. From the chemical analysis, this polysaccharide was found to be a P-1,3-n-glucan consisting essentially of the same repeating units as found for schizophyllan. The light scattering and viscosity measurements yielded the following results: (!)The weight-average molecular weights Mw of the two scleroglucan samples in 0.01 N NaOH are roughly three times as large as those in DMSO, (2) (4) [IJ] of the sonicated sample in water+DMSO mixtures undergoes an almost discontinuous decrease at about 87 wt% DMSO at which the schizophyllan triple helix dissociates to single chains. Based on these results and structural information, it was concluded that the scleroglucan studied exists in 0.01 N NaOH as a triple helix similar to that of schizophyllan in either pure water or 0.01 N NaOH, while it is dispersed in DMSO as a single chain and behaves like an unperturbed flexible chain.KEY WORDS Polysaccharide I Scleroglucan I Schizophyllan I Triple Helix I Chemical Structure I Molecular Weight I Radius of Gyration 1 Intrinsic Viscosity I Scleroglucan is the general name for capsular polysaccharides produced by species of the genus sclerotium including a fungus sclerotium glucanicum. One of these polysaccharides is commercially available under the trade name of Polytran (Ceca S. A., France). According to a technical report 1 of Ceca S. A., this scleroglucan is water-soluble and nonionic. ed to be the same polysaccharide as schizophyllan.A long time ago, Johnson et a/. 2 investigated the chemical structure of a scleroglucan from an unidentified species of sclerotium and concluded that this polysaccharide was a P-1 ,3-o-glucan consisting of the repeating units shown in Figure I. These repeating units are exactly the same as those reported for schizophyllan, 3 .4 an extracellular polysaccharide produced by a fungus schizophyllum commune. Thus, scleroglucans are usually considerIn this paper, we report a study made on a sample of Polytran scleroglucan and its sonicated fragment in order to examine whether scleroglucan is chemically identical with schizophyllan and whether these two polysaccharides show the same dimensional and hydrodynamic behavior in dilute solution. For the former problem, we applied the same methods of chemical analysis as those established for schizophyllan. 4 For the latter problem, we determined the weight-average molecular weights, radii of gyration, and intrinsic viscosities of the two samples in 0.01 N sodium hydroxide (NaOH) and dimethylsulfoxide (DMSO), m which schizophyllan dissolves as a rodlike triple 1135
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