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.