Towards regioselective synthesis of oligosaccharides by use of alpha-glucosidases with different substrate specificity

alpha-Glucosidase from two microbial sources, Bacillus stearorthermophilus and Brewer's yeast, has been used to catalyze transglycosylation reactions and a comparative study was carried out to determine the regioselectivity o f this reaction. Bacterial alpha-glucosidase exhibited higher transfer acti vity with maltose and was able to synthesize tri- and tetrasaccharides in h igh yield (27%). In the case of yeast enzyme, only trisaccharides were synt hesized in lower yield. Structure analysis of transglycosylation products b y means of GC-MS and NMR spectroscopy revealed a correlation between the hy drolytic substrate specificity and the regioselectivity of transglycosylati on reaction. Higher substrate specificity of bacterial enzyme, however, inf luenced its transglucosylation activity toward other saccharide accepters. (C) 1999 Elsevier Science Ltd. All rights reserved.