固定化葡萄糖异构酶最适pH值的调节

用多孔强碱性三乙醇胺基聚苯乙烯树脂作为载体,用CNBr与载体上多羟基作用共价偶联葡萄糖异构酶(GI)。最适偶联条件表明:CNBr量增多,蛋白载量增加,但比活下降。固定化葡萄糖异构酶(IGI)最适反应温度比天然酶提高15℃。并系统地研究了影响IGI活力-pH的曲线的各种因素:用具有不同平均孔径的载体(R=137A,185A,230A,365A)固定化GI,在低离子强度条件下(0.0064mol/L),测定其最适pH值分别7.76,7.56,7.50,8.20。选择平均孔径为230A且具有不同数量三乙醇胺基的载体(0.94,1.05,1.13,1.37mmol/g干胶)分别固定化GI,其最适pH值分别为7.70,7.50,7.46,7.36。

Effect of Optimum pH on Immobilized Glucose Isomerase

Glucose Isomerase (GI) was coupled on porous triethanolaminepolystyrene (TMPS) resin by CNBr.Protein binding capacity increased with the increase of the CNBr concentration but its specific activity decreased.The optimum temperature of Immobilized Glucose Isomerase (IGI) was higher than that of native GI.Some kinds of factor that influence the activity-pH profile of IGI has been systemically investigated.Because of pore diffusion-limited to the hydrogen ion and the effect of ionic groups, hydrogen ion concentration in the microenviroment was lower than that in the bulk solution.Consquently, the apperent Optimum pH of IGI was shifted toward acid pH values.Using the beads with different average radius of pores(137A, 185A, 230A, 365A) as carriers, the apperent optimum pH of IGI, at lower ionic strength (0.0064mol/L) , was fouud to be shifted to 7.76, 7.56, 7.50, 8.20 respectively.Usiug the beads with different amount amount of ion groups (0.94, 1.05, 1.13, 1.37mmol/g dry gel) as carriers, the apperent optimum pH of IGI was shifted to 7.70, 7.50, 7.46, 7.36 respectively.