Glucans, fractionation

Analysis of nb/lcb glucan fractions obtained from a preparative S-200/S-1000 system... 

Comparison of separation performance for quanrificarion of a high dp scb glucan fraction in a nb/lcb glucan sample... 

Figure 16.15 shows the resulting chromatograms for the three glucan fractions obtained by previous preparative separation on Sephacryl S-200/S-1000 (Fig. 16.14). From the normalized fraction chromatograms, the elution profile of the initial mixture has been reconstructed by mixing 50% fraction 1, 40% fraction 2, and 10% fraction 3. Compared to the chromatogram of the preparative Sephacryl S-200/S-1000 system, separation with the TSK/ Superose system yields improved resolution in the low dp (high V, ) domain.

The molecular uniformity of constituting components of a nb/lcb glucan fraction of potato starch was investigated with Sepharose CL 2B (Fig. 16.16) as well as with Sephacryl S-1000 (Fig. 16.17). Therefore, each of the subsequently eluted 3-ml fractions was analyzed on their potential to form inclusion complexes with iodine, a sensitive test for the presence of nb/lcb glucans. Results are shown in Fig. 16.17 in terms of branching index, the ratio of extinction of pure iodine solution and of nb/lcb glucan/iodine complex the higher the index, the more pronounced the nb/lcb characteristics. 

Enzymic hydrolysis of a jS-D-glucan fraction from the cell wall of Piricularia oryzae454,455 released 3-O-gentiobiosyl-D-glucose (118) and gen-tiotriose, indicating possible differences in structure from that of the polymer separated from Sclerotium sp. On reaction of the alkali-insoluble glucan... 

The cell-wall j3-D-glucan fractions, insoluble in alkali and acid, from wild and from a mutant S. cerevisiae have been compared. Methylation analysis indicated more 1,3- and 1,3,6-linked D-glucosyl residues, and fewer 1,6-linked in the latter. The wild type was hydrolyzed less by exo-(l- 3)-/3-D-glucanase and more by endo-(l -> 6)-/3-D-glucanase than was the glucan from the mutant, consistent with the methylation data.4733... 

In some cases, a-linked glucan fractions have also been isolated,56 62 and the preliminary investigations suggest that these consist mainly of starch-like polysaccharides. 

A third portion detectable only by x-ray diffraction was associated with other components and could not be extracted, even with prolonged boiling. It wa,s removed by hot dilute alkali and was associated in the wall with another glucan fraction. 

An extracellular polysaccharide (D-glucan) fraction from culture filtrates of Forms fomentarius exhibited anti-tumour activity towards Ehrlich ascites carcinoma. ... 

This Asian fungus is the second most commonly cultivated edible Tricholomataceae] mushroom also used for medicinal purposes (II). It contains immunostimuiating polysaccharides, including linear (l->3)-p-D-glucans. Lentinan, a polysaccharide (P-D-glucan) fraction from L edodes has been studied more extensively and displays greater antitumor activity than other similar substances (12). Lentinan appears active in certain animals against various tumors (13). 

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