Enzymatic synthesis of a novel cyclic pentasaccharide consisting of α-d-glucopyranose with 6-α-glucosyltransferase and 3-α-isomaltosyltransferase Original Research Article

A novel cyclic pentasaccharide (CPS) and a branched cyclic pentasaccharide (6G-CPS) consisting of d-glucopyranose were synthesized with 6-α-glucosyltransferase (6GT) and 3-α-isomaltosyltransferase (IMT) from Bacillus globisporus N75. The structure of CPS was cyclo-{→6)-α-d-Glcp-(1→3)-α-d-Glcp-(1→6)-α-d-Glcp-(1→3)-α-d-Glcp-(1→4)-α-d-Glcp-(1→}. The other, 6G-CPS, had the structure cyclo-{→6)-α-d-Glcp-(1→3)-α-d-Glcp-(1→6)-α-d-Glcp-(1→3)-[α-d-Glcp-(1→6)]-α-d-Glcp-(1→4)-α-d-Glcp-(1→}. The formation of CPS was presumed to occur after the following four successive reactions: a 6-glucosyltransfer reaction with 6GT, a 4-glucosyltransfer reaction with 6GT, a 3-isomaltosyltransfer reaction with IMT, and a cyclization reaction with IMT.