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Glycogens from mammalian and invertebrate sources have been compared by measuring the iodine-staining spectra of the debranched polymers and the debranched beta-amylase limit dextrins. From the results, it is concluded that, whereas the interior chains of each group of glycogen are very similar, the exterior chains of the mammalian glycogens generally contain a small number of longer chains which are not found in the invertebrate glycogens.

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Treatment of cells and purified cell walls of the fission yeast Schizosaccharomyces pombe with primuline reveals the septum as a bright fluorescent band. When polysaccharides containing (1----3)-beta-, (1----6)-beta- or (1----3)-alpha-glucosidic linkages are treated with primuline, only those molecules containing chains of (1----3)-beta-glucosyl residues are stained. This implies that (1----3)-beta-glucan is present in the septum of Schiz. pombe as the main constituent.

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Isoamylase has been prepared by affinity chromatography of a commercial enzyme-preparation from a strain of Cytophaga (also known as a Flavobacterium or Polyangium). The enzyme was not very stable, but the stability could be improved by calcium ions. The enzyme had a very low but significant activity on pullulan and on alpha-dextrins having maltosyl side-chains. This observation, which is contrary to previous reports, has been related to the specificity of isoamylase and other bacterial debranching-enzymes.

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An alkali-soluble glucan from the cell walls of Saccharomyces cerevisiae NCYC1109 has been hydrolysed with a purified endo-(1 leads to 3)-beta-D-glucanase and an endo-(1 leads to 6)-beta-D-glucanase from Bacillus circulans WL-12. The products of enzyme action include various oligosaccharide and polysaccharide fractions which have been separated by gel filtration and characterized, giving new information on the fine structure of the glucan. The isolated cell walls have also been subjected to enzymic hydrolysis. The results suggest that part of the cell-wall mannan is held in place by a glucan component.

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A limit dextrinase, free from contaminating carbohydrases, has been purified from malted sorghum flour. The enzyme readily hydrolysed alpha-limit dextrins having maltosyl or maltotriosyl side-chains, pullulan, and amylopectin beta-limit dextrin. Glycogen beta-limit dextrin and amylopectin were more slowly hydrolysed, the detection of the hydrolysis of amylopectin being dependent on enzyme concentration. No significant debranching of glycogen could be detected.

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A commercial enzyme preparation, of fungal origin, contained a mixture of beta-D-glucanases which were fractionated by ion-exchange chromatography to give a mixture of an endo-(1 leads to 4)- and an exo-(1 leads to 3)-beta-D-glucanase. These two enzymes were then separated by molecular-sieve chromatography on Sephadex G-150. The purified exo-(1 leads to 3)-beta-D-glucanase has a relatively high specificity for (1 leads to 3)-beta-D-glucosidic linkages, and has no action on lichenin.

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Two endo-beta-D-glucanases which act, respectively, on (1 leads to 3)-beta-D-glucans and barley beta-D-glucan have been isolated from malted barley, and purified by ion-exchange chromatography. The latter enzyme is highly specific for barley beta-D-glucan, and has no action on either (1 leads to 3)- or (1 leads to 4)-beta-D-glucans. It will also act on dyed barley-beta-D-glucan. Certain group-specific reagents inhibit the endo-barley-beta-D-glucanase and the endo-(1 leads to 3)-beta-D-glucanase to similar extents.

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An alkali-soluble glucan was obtained from the cell walls of Saccharomyces cerevisiae NCYC1109 and baker's yeast by extraction with cold, dilute sodium hydroxide under nitrogen. The glucan, which represented approximately 20% of purified glucan was homogeneous and was shown to be free from contamination by other cell-wall polysaccharides by ultracentrifuging, gel filtration and electrophoresis. In addition to glucose, the glucan contained traces of mannose and nitrogen, but no hexosamine. Structural analyses revealed the presence of 80-85% (1 leads to 3)-beta-D linkages, 8-12% (1 leads to 6)-beta-D linkages and 3-4% branched residues linked through C-1, C-3 and C-6. The molecular weight of the glucan was estimated to be about 250000. Electron-microscopic examination of the cell walls after alkali extraction showed that an amorphous surface layer had been removed revealing numerous bud scar structures.

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The limit dextrinases from ungerminated oats and rice have been purified, and their substrate specificity compared with a bacterial isoamylase preparation. Both cereal enzymes could hydrolyse (1 yields6)-alpha-D-glucosidic linkages in oligosaccharide alpha-dextrins, pullulan, amylopectin, and the beta-limit dextrins of amylopectin and glycogen. However, under comparable conditions, they were unable to attack glycogens.

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Yeast glucan as normally prepared by various treatments of yeast (Saccharomyces cerevisiae) cell walls to remove mannan and glycogen is still heterogeneous. The major component (about 85%) is a branched beta-(1-->3)-glucan of high molecular weight (about 240000) containing 3% of beta-(1-->6)-glucosidic interchain linkages. The minor component is a branched beta-(1-->6)-glucan. A comparison of our results with those of other workers suggests that different glucan preparations may differ in the degree of heterogeneity and that the major beta-(1-->3)-glucan component may vary considerably in degree of branching.

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