Enzymatic synthesis of a novel cyclic pentasaccharide consisting of alpha-D-glucopyranose with 6-alpha-glucosyltransferase and 3-alpha-isomaltosyltransferase

摘要

A novel cyclic pentasaccharide(CPS)and a branched cyclic pentasaccharide(6G-CPS)consisting of D-glucopyranose were synthesized with 6-alpha-glucosyltransferase(6GT)and 3-alpha-isomaltosyltransferase(IMT)from Bacillus globisporus N75.The structure of CPS was cyclo-{->6)-o(-D-Glcp-(1->3)-alpha-D-Glcp-(1->6)-alpha-D-Glcp-(1->3)-alpha-D-Glcp-(1->4)-alpha-D-Glcp-(1->}.The other,6G-CPS,had the structure cyclo-{->6)-alpha-D-Glcp-(1->3)-alpha-D-Glp)-(1->6)-alpha-D-Glcp-(1->3)-[alpha-D-Glcp-(1->6)]-alpha-D-Glcp-(1->4)-alpha-D-Gcp-(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.