Chemoenzymatic synthesis of modified maltooligosaccharides from cyclodextrin derivatives.

Methyl and p-nitrophenyl alpha-maltooligosaccharides with a 3,6-anhydro ring on the fourth glucosyl residue, starting from the reducing end, were prepared. Enzymatic coupling catalyzed by CGTase, between 3A,6A-anhydrocyclomaltohexaose and methyl or p-nitrophenyl alpha-D-glucosides led to maltohepatosides. When miglitol, a nojirimycin analogue was used, maltooligosaccharides with miglitol at the reducing end were also obtained. After glucoamylase digestion, maltopentaosides with a 3,6-anhydro glucose as antepenultimate unit were produced in good yield. The same methyl maltopentaoside was also obtained when 3A,6A-anhydrocyclomaltoheptaose was incubated with methyl alpha-D-glucoside and CGTase, glucoamylase, glucose oxidase and catalase. These results provided new information about the specificity of the subsites of CGTase.