Isomaltose synthesis in the reversed hydrolysis catalyzed by amyloglucosidase immobilized in the thermosensitive gel

Thermally sensitive poly(N-isopropylacrylamide/acrylamide) gel, which exhibits a thermal property of a lower critical solution temperature (LCST), was applied as a carrier immobilizing amyloglucosidase (AG) in order to form a glycosidic bond. Isomaltose and maltose were produced from glucose in a process of reverse reaction of hydrolysis using immobilized AG. Isomaltose was accumulated predominantly in the enzymatic reaction with 2 mol dm−3 glucose solution, while AG hydrolyzed maltose to glucose in the process. The yield of isomaltose was 13 times as much as that of maltose catalyzed by the immobilized AG under the swelling state of the gel at 20 °C. The role of polymer gel for isomaltose synthesis was discussed in connection with the LCST.