Microgel-Catalyzed Hydrolysis of Nonactivated Disaccharides

Abstract

The controlled and selective hydrolysis of underivatized disaccharides and oligosaccharides remains a challenge that is met by enzymatic and nonenzymatic approaches. In an effort to capitalize on recent progress in the development of functional enzyme mimics for the hydrolysis of glycosidic bonds, we developed cross-linked microgels with embedded binuclear copper(II) complexes that are shown here to hydrolyze 1→4 over 1→6 glycosidic bonds under mildly alkaline conditions at elevated temperatures. The microgel catalysts show an unusual preference for the hydrolysis of 1→4β- over 1→4α-glycosidic bonds yielding up to 25 μg L–1 of glucose from cellobiose over 72 h and about half of that during the hydrolysis of maltose after correction for background effects. The experimental results are supported by computational analyses of the interactions between the embedded catalyst and the nonactivated disaccharide in putative transition state structures of the assembly during hydrolysis of the nonactivated glycosidic bond to rationalize this observation.