A Comparison of the Structure of Curdlan and Pachyman

The fine structure of curdlan produced by Alcaligenes faecalis var. myxogenes 10C3, mutant K, and pachyman from Poria cocos were investigated, with regard to their gel-forming properties. Periodate oxidation showed that both polysaccharides contain very high proportions of (1→3)-linked glucose residues. On complete hydrolysis the glucan polyalcohol obtained by periodate oxidation and borohydride reduction of curdlan (DP¯ 455) gave glucose and glycerol, in the molar ratio of 125~130: 1, and on mild acid hydrolysis yielded degraded polysaccharide (DP¯ 155), confirming the previous conclusion that curdlan has an essentially unbranched structure though it may contain a few internal (1→6)-glucosidic linkages. On complete hydrolysis the glucan polyalcohol derived from pachyman (DP¯ 255) gave glucose and glycerol, in the ratio of 40:1, and on mild hydrolysis it yielded degraded polysaccharide (DP¯ 130). This indicates that pachyman contains on the average four branch points and one internal (1→6)-glucosidic linkage in the molecule.