Acceptor specificity of trehalose phosphorylase from Thermoanaerobacter brockii: Production of novel nonreducing trisaccharide, 6-O-α-D-galactopyranosyl trehalose

We investigated the acceptor specificity of a thermostable trehalose phosphorylase from Thermoanaerobacter brockii ATCC 35047 (TbTP) was examined using β-D-glucose-1-phosphate (β-G1P) as a glucosyl donor and oligosaccharides as the acceptor. Oligosaccharides with a reducing-end glucose residue as the C-6 substituent (e.g., isomaltose, gentiobiose, melibiose, isomaltotriose, and isopanose) were found to be successful acceptors. The transfer products of isomaltose, gentiobiose, and melibiose were isolated and characterized as 6-O-α-D-glucopyranosyl trehalose (α-GlcTre), 6-O-β-D-glucopyranosyl trehalose (β-GlcTre), and 6-O-α-D-galactopyranosyl trehalose (α-GalTre), respectively. To produce α-GalTre, a novel nonreducing trisaccharide, the reaction conditions of α-GalTre were examined using trehalose as a glucosyl donor. As a result, the yield of α-GalTre reached 40.5%.