Patent ID: 7078194

Claim:
A method for synthesizing a glycoside product, (a) selecting a glycoside product which is a substrate for a wild-type glycosidase enzyme having two catalytically active amino acids with carboxylic acid side chains within the active site; (b) combining in a reaction mixture (i) a mutant form of the glycosidase enzyme, said mutant enzyme having one of said catalytically active amino acids of the glycosidase enzyme substituted with a different amino acid of comparable or smaller size, said different amino acid having a non-carboxylic acid side chain, wherein said mutant glycosidase does not catalyze the hydrolysis of the glycoside product and retains the activity to synthesize the glycoside product; and (ii) a glycosyl donor molecule comprising a sugar linked to a leaving group and a glycoside acceptor molecule, said glycosyl donor molecule having a β configuration and said glycoside acceptor molecule having an α configuration, or vice versa, wherein said glycoside acceptor molecule and said glycosyl donor molecule are selected so as to form a glycosidic bond which is hydrolyzed by the wild-type glycosidase enzyme; and (c) allowing the mutant glycosidase enzyme to enzymatically couple the glycosyl donor molecule and glycoside acceptor molecule to synthesize the glycoside product.