A new trisaccharide, 3G-.ALPHA.-D-glucosyl-sucrose, synthesized by the transglucosidase action of immobilized buckwheat .ALPHA.-glucosidase.

Enzymatic synthesis of α-glucosyl-sucrose through the transglucosidase action of immobilized buckwheat α-gl cosidase was attempted in a reaction system containing maltose and sucrose. Three kinds of nonreducing trisaccharides were produced, and a large portion of the trisaccharide was 4G- α-D-glucosyl-sucrose (erlose). Another was a new trisaccharide, O-α-D-glucopyranosyl-(1→3)-O-α-D-glucopyranosyl-(1→2)-O-β-D-fructofuranoside (3G-α-D-glucosyl-sucrose; [α]D+120°, in water), and the other was 6G-α-D-glucosyl-sucrose (theanderose; [α]D+ 107°, in water). The new trisaccharide was named "esculose."