Immobilization of N-acetylneuraminic acid aldolase and properties of the Immobilized Enzyme

N-acetylneuraminic acid aldolase (NAL) was immobilized using LX-1000HFA amino resin. The immobilization conditions were optimized, and the enzymatic properties and stabilities of free and immobilized enzymes were compared. The optimum conditions of immobilization were obtained that the quantity of carrier was 5.0 g, the immobilization time was 12 h, the buffer concentration was 1.0 mol/L, the pH was 7.5, and the temperature was 25 ℃.The prepared immobilized NAL has the highest viability and the enzyme activity could reach 200 U/g wet resin. Compared with the free enzyme, the optimum reaction temperature was increased by 5 ℃, the optimum reaction pH was not changed, and thermal - stability and operating – stability were significantly improved. At the same time, the storage stability and operational stability of the immobilized enzyme were also greatly enhanced. Only 6% of the enzyme activity is lost after storage for 10 days at 4 ℃. And the immobilized enzyme retained 80% enzyme activity after repeated usage for 10 times. The immobilized enzyme had good thermal stability, pH stability, storage stability, and operational stability, which provided a theoretical basis for the industrial production of N-acetylneuraminic acid by enzymatic method.