DISACCHARIDE PRODUCTION BY GLUCOAMYLASE IN AQUEOUS ETHER MIXTURES

Five alpha-linked diglucosyl disaccharides (isomaltose, nigerose, koji biose, maltose, and alpha,beta-trehalose) and two trisaccharides (isom altotriose and panose) were produced in 90% aqueous solutions of 2-met hoxyethyl ether, 2-ethoxyethyl ether, or triethylene glycol dimethyl e ther by glucoamylase-catalyzed glucose condensation. Precipitation of the products and phase separation caused higher net production of disa ccharides than expected by comparison with the same reactions occurrin g in solvent-free solutions. Glucoamylase was equally stable in water and in aqueous 90% 2-methoxyethyl ether, but was stabilized by further decreases of water concentration. Aqueous ethers neither modified the product specificity of glucoamylase nor changed the relative order of initial rates of disaccharide formation. Because of its broad specifi city (five disaccharides and two trisaccharides), glucoamylase would n ot be a suitable biocatalyst for oligosaccharide synthesis.