Immobilization Of Glucose Isomerase And Its Performance Study

The polymer carrier GAMM with epoxy groups was synthesized by the inverse suspension polymerization, in which Tween-20 and Span-60 were used as the complex dispersants, and N, N'-methylene-bis (acryla-mide) (MBAA) as crosslinking agent, and ally glycidol ether (AGE) and glycidyl methacrylate (GMA) were used as reactive monomers. The carrier was used to immobilize glucose isomerase (GI), in which effects of immobilization conditions and isomerization reaction conditions on the activity of immobilized GI and the operating performance of immobilized GI were investigated.The optimum immobilization conditions were as follows:the loading amount of free GI was 0.3 mL per gram carrier, the immobilization temperature was 25℃, and the immobilization time was 24 h; The optimum reaction pH values of free and immobilized GIs were both 7.5. Immobilized GI was more stable at pH value of 5-7.5 and had wider application pH range, The optimum reaction temperature was 65℃. As for free and immobilized GIs, the kinetic parameters were calculated as 0.36 and 1.16 mol/L for Km, and 1.3×10-3 and 1.1×10-3 mol/L·min for Vmax, respectively. The maximum activity of immobilized GI was 450 U/g (wet). The relative activity of immobilized GI was about 90% after recycled for 18 times and retained 97%of its initial activity after stored at 4℃for six weeks, immobilized GI had better thermal stability than free GI below 80℃.