Synergistic Catalysis of Glycosyltransferase and Sucrose Synthase to Produce Isoquercitrin Through Glycosylation of Quercetin

Isoquercitrin exhibits a number of biological properties and has a higher water solubility than quercetin. In this work, an Arabidopsis glycosyltransferase with high activity on quercetin (AtUGT78D2) was coupled with an efficient quercetin-tolerant Glycine max sucrose synthase (GmSUS) to synthesize isoquercitrin by regenerating UDP-glucose from UDP. The important factors for optimal synergistic catalysis were determined. Through the use of a fed-batch operation, the final titer of isoquercitrin increased to 3830 mg/L with a corresponding molar conversion of 94.3% and a maximum number of UDP-glucose regeneration cycles (RCmax) of 33.