Convenient Synthesis of β-(1→3)-Galactosyl Disaccharide α-Glycoside and Its Analogs as Mimic Units of Mucin-Type Carbohydrate

: beta-Galactosidase from porcine testes induced regioselective transglycosylation from lactose to the 3-position of 2-acetamido glycosides. When alpha-D-GalNAc-OC6H4NO2-p was used as an acceptor, the enzyme synthesized mainly beta-D-Gal-(1-->3)-alpha-D-GalNAc-OC6H4NO2-p with its (1-->6) linked isomer. The use of an inclusion complex of the glycoside acceptor with beta-CD increased the efficiency of transglycosylation by increasing the solubility of the acceptor. In the same way, the use of beta-D-GalNAc-OC6H4NO2-p as acceptor led to the preferential synthesis of beta-D-Gal-(1-->3)-beta-D-GalNAc-OC6H4NO2-p over that of its (1-->6) linked isomer. beta-D-Gal-(1.3)-beta-D-GlcNAc-OC6H4NO2-p was also synthesized with beta-D-GlcNAc-OC6H4NO2-p acceptor by the consecutive use of beta-D-galactosidases from porcine testes and Bacillus circulans. These enzyme reactions are efficient enough to allow the one-pot preparation of the desired disaccharide glycosides.