Abstract
Structurally modified dextran was produced by the action of cyclodextrin glucanotransferase (CGTase) on clinical dextran. The dormant activity of CGTase was further confirmed by using the enzyme preparation from a different source. Although an increase in reducing sugar in the reaction mixture was small, a clear difference in the molecular weight distribution of CGTase-treated dextran was observed, as in previous experiments. Therefore the susceptibility of CGTases on dextran was verified with the other origin of CGTase. CGTase-treated dextran showed a higher interaction with Con A and fluorescent reagent, 6-p-toluidinylnaphthalene-2-sulfonate. The susceptibility of CGTasetreated dextran to isoamylase and glucoamylase varied significantly according to the reaction temperatures for the CGTase action. NMR-HMQC and methylation analyses both indicated additional occurrence of α-1, 4-branch points in the dextran molecule, which opposed the knowledge of sole branch point of -1, 3-linkages in the dextran. CGTase action seemed to increase the content of α-1, 4-branch points in the CGTase- treated dextran by introducing the cleaved fragments as the new branch into the back bones of α-1, 6-linkages. These results suggested that CGTasetreated dextran had increasing amounts of α-1, 4-branch points, which caused the structural changes demonstrated by the above analysis.
