CHARACTERISTICS OF GLUCOAMYLASE IMMOBILIZ ED ON MEMBRANE AND PERFORMANCE OF MEMBRANE REACTOR

Glucoamylase was immobilized on a capillary membrane by the glutaralde hyde crosslinkage method. The membrane has an asymmetric structure and contains a great number of amino groups in porous areas. Maltose was used as substrate and was forced by applying pressure to permeate thro ugh the membrane. The amount of enzyme immobilized showed high density such as mg protein per cm(2) of membrane, and its specific activity w as 20% that of free enzyme. Optimum pH and temperature of enzyme were not changed by immobilization. Km and Ki values were lower than those of free enzyme when enzyme was immobilized on the membrane in low dens ity. But, as the amount of enzyme immobilized increased, both of these values increased. In continuous operation, the activity of enzyme imm obilized was stable, glucose content in permeate was more than 95% and flux decreased very slightly during 600 hours. The reaction using 30( w/v)% maltose solution was performed by setting a short residence time in the membrane and the obtained permeate once again permeated throug h the immbilized membrane. Glucose content attained 96% in permeate wi thout containing isomaltose, and in glucose content of 97.5% in permea te, isomaltose of 0.2% was formed. This two-step reaction was effectiv e for producing pure product because the reverse reaction was suppress ed.