抄録
The structure of dextran synthesized from maltotetraose by dextrin dextranase (EC 2.4.1.2) from Acetobacter capsulatus ATCC 11894 was analyzed. When the Acetobacter dextran (AD) was acetolyzed, glucose and maltose were produced. AD was allowed to react with α-amylases. AD was digested by bacterial saccharifying α-amylase and bacterial liquefying α-amylase, and glucose, maltose, and maltotriose were produced. The structure of the fraction obtained from dextranase-digested AD by activated charcoal chromatography, which did not contain glucose, isomaltose, and isomaltotriose, was investigated by methylation analysis, and the ratio of 2, 3, 4, 6-tetra-O-methyl- : 2, 3, 4-tri-O-methyl- : 2, 3, 6-tri-O-methyl- : 2, 3-di-O-methyl-alditol acetate was estimated as 22.9 : 46.8 : 15.5 : 14.8. This result indicated the existence of α-1, 4 branches and that of α-1, 4 linkages in α-1, 6 glucosyl linear chains. Native AD was calculated to be constructed with 6.23 branching points and 6.53 α-1, 4 linked glucosyl residues per 100 glucosyl units. Though AD was digested slightly by rat intestinal acetone powder, high molecular weight polymers remained. Therefore AD could be used as a dietary fiber.
