Mechanism-oriented redesign of an isomaltulose synthase to an isomelezitose synthase by site-directed mutagenesis.

An isomelezitose synthase was redesigned out of the sucrose isomerase from Protaminobacter rubrum for the synthesis of isomelezitose (6-O(F)-glucosylsucrose), a potential nutraceutical. The variants F297A, F297P, R333K, F321A_F319A and E428D catalyze the formation of isomelezitose in up to 70 % yield.