Synthesis by an α-Glucosidase of Glycosyl-trehaloses with an Isomaltosyl Residue

Abstract

Glycosyl-trehaloses with an isomaltosyl residue were synthesized by α-glucosidase from Aspergillus niger by using maltotetraose as a glucosyl donor and trehalose as the acceptor. The one trisaccharide and two tetrasaccharides formed were isolated by successive column chromatography. The results of an enzymatic digestion, methylation analysis, and ¹³C-NMR studies indicated that these oligosaccharides were α-isomaltosyl α-glucoside, α-isomaltotriosyl α-glucoside and α-isomaltosyl α-isomaltoside. These oligosaccharides were not fermented to an acid by Streptococcus mutans, and they effectively inhibited water- insoluble glucan synthesis from sucrose by glucosyltransferase. In an in vitro utilization test with human intestinal bacteria, these oligosaccharides were predominantly utilized by Bifidobacteria.

Key words:

• trehalose
• isomaltosyl
• residue
• α-glucosidase