Enzymatic synthesis of 3-O-methyl-4-O-β-d-galactopyranosyl-d-glucose (3-O-methyl-lactose); a potential agent for the assessment of intestinal lactase activity

Enzymatic synthesis of 3-O-methyl-4-O-β-d-galactopyranosyl-d-glucose (3-O-methyl-lactose) has been attempted using both galactosyltransferase and galactosidase activities. The transferase-catalysed reaction produces exclusively the desired product in β-1,4-glycosidic linkage whereas the galactosidase-catalysed reactions predominantly form a 1,6-linked disaccharide. With galactosidase, in order to change the regioselectivity, blocking of the 6-position of 3-O-methyl-d-glucose and anomeric modification of the acceptor structure were investigated. Although acetylation of the 6-position of 3-O-methyl glucose catalysed by lipase was successful, the synthesis of the desired disaccharide did not occur.