The action of transglucosidase of Aspergillus oryzae on maltose.

In 1950 Pan and his associates (1) reported the conversion of maltose into non-fermentable sugars by an enzyme solution obtained from Aspergillus niger. They isolated a crystalline, non-fermentable, reducing trisaccharide from the reaction mixture (2). Structural studies by French (3) and by Wolfrom et al. (4) have shown this trisaccharide to be a 4-a-isomaltosyl-n-glucose (panose). In a preliminary note (5) we described an enzyme of Aspergillus oryxae which also synthesizes the trisaccharide panose from maltose. Other products of enzyme action on maltose were the disaccharide isomaltose, the trisaccharide 6-ar-isomaltosyl-D-glucose (dextrantriose), and the tetrasaccharide 4-or-dextrantriosyl-n-glucose.1 Since all the synthesized compounds are formed by a transglucosidation reaction, it is probable that only one enzyme is involved in their formation. In the present paper we present evidence for the mechanism of action of this enzyme on maltose and record the identification of the products of its action.