Characterization of the immobilized beta-galactosidase C from Bacillus circulans and the production of beta(1-3)-linked disaccharides

A recombinant beta-galactosidase, which was obtained from the beta-galactosidase C gene of Bacillus circulans and cleaves the non-reducing end galactosyl residue of beta(1 to 3)-linkages selectively, was immobilized using CNBr-Sepharose. Although the effect of pH was not changed by the immobilization, the thermostability and stability in the presence of DMF were increased. Optimization of the transglycosylation using para-nitrophenyl beta-d-galactopyranoside as a donor and benzyl-alpha-D-N-acetylgalactosaminide as an acceptor afforded a beta(1 to 3)-linked disaccharide derivative with 62% molar yield in a gram scale synthesis. Using the methyl-analogue as an acceptor, 53% of the acceptor was converted to the respective beta(1 to 3)-disaccharide