Immobilization of glucose isomerase onto GAMM support for isomerization of glucose to fructose

Glucose isomerase (GI) from Streptomyces rubiginosus was immobilized covalently onto GAMM support prepared by our patented inverse suspension polymerization with glycidyl methacrylate (GMA), ally glycidyl ether (AGE), N,N′-methylene-bis(acrylamide) (MBAA), and acrylamide (MAA), and used for isomerization of glucose to fructose. Effects of immobilization conditions and reaction conditions on the activity of immobilized GI, the kinetic parameters, the operational stability, thermal stability and storage stability of immobilized GI were investigated. The optimum immobilization conditions were GI addition amount of 0.3 ml GI/g support, immobilization time of 24 h, and immobilization temperature of 25 °C. The optimum reaction conditions were pH value of reaction solution of 7.5 and reaction temperature of 65 °C. The activity of immobilized GI was 450 U/g (wet). Km and Vmax values of immobilized GI were 1.16 mol/L and 1.07 × 10−3 mol/L min, respectively. Immobilized GI onto GAMM support has better operational stability, thermal stability and storage stability, in which it retained 91% of its initial activity after recycled for 18 times and retained 97% of its initial activity after stored at 4 °C for six weeks. Therefore immobilized GI onto GAMM support was an excellent catalyst for isomerization of glucose to fructose.