Enzymatic Synthesis and Structural Characterization of Novel Trehalose-Based Oligosaccharides

Trehalose, alpha-D-glucopyranosyl-(1 <-> 1)-alpha-D-glucopyranoside, is a disaccharide with multiple effects on the human body. Synthesis of new trehalose derivatives was investigated through transgalactosylation reactions using beta-galactosidase from four different species. beta-galactosidases from Bacillus circulans (B. circulans) and Aspergillus oryzae (A. oryzae) were observed to be the best biocatalysts, using lactose as the donor and trehalose as the acceptor. Galactosyl derivatives of trehalose were characterized using nuclear magnetic resonance spectroscopy. Trisaccharides were the most abundant oligosaccharides obtained followed by the tetrasaccharide fraction (19.5% vs 8.2% carbohydrates). Interestingly, the pentasaccharide [beta-Galp-(1 -> 4)](3)-trehalose was characterized for the first time. Greater oligosaccharide production was observed using beta-galactosidase from B. circulans than that obtained from A. oryzae, where the main structures were based on galactose monomers linked by beta-(1 -> 6) and beta-(1 -> 4) bonds with trehalose in the ending. These results indicate the feasibility of commercially available beta-galactosidases for the synthesis of trehalosederived oligosaccharides, which might have functional properties, excluding the adverse effects of the single trehalose.