Chang Min-Yun, Juang Ruey-Shin
Department of Chemical Engineering, National United University, Miao-Li 360, Taiwan, ROC.
Int J Biol Macromol. 2007 Feb 20;40(3):224-31. doi: 10.1016/j.ijbiomac.2006.07.009. Epub 2006 Jul 31.
Equal weights of chitosan and ZrO2 powders were mixed in acetic acid solution to prepare the composite beads. They were then cross-linked with glutaraldehyde and stored with and without freeze-drying before use. The physicochemical properties of acid phosphatase immobilized on four types of the supports (wet/dried pure chitosan beads, wet/dried chitosan-ZrO2 composite beads) were compared. Various parameters including glutaraldehyde concentration, cross-linking time, enzyme concentration, temperature, and pH on enzyme activity were studied. It was shown that the activity yield of enzyme immobilized on the dried chitosan-ZrO2 beads was the highest, and the relative activity remained above 83.2% within pH 2.9-5.8. Regardless of wet or dried beads, the Michaelis constant KM and maximum rate of reaction Vmax of acid phosphatase immobilized on chitosan-ZrO2 composite beads were 1.8 times larger than those on pure chitosan beads. Of the four immobilized enzymes, the use of wet chitosan-ZrO2 bead as the support showed the lowest thermal deactivation energy (78 kJ mol(-1)).
将等量的壳聚糖和二氧化锆粉末在乙酸溶液中混合以制备复合珠。然后将它们用戊二醛交联，并在使用前进行冻干或不冻干保存。比较了固定在四种类型载体（湿/干纯壳聚糖珠、湿/干壳聚糖 - 二氧化锆复合珠）上的酸性磷酸酶的物理化学性质。研究了包括戊二醛浓度、交联时间、酶浓度、温度和pH等各种参数对酶活性的影响。结果表明，固定在干燥壳聚糖 - 二氧化锆珠上的酶的活性产率最高，并且在pH 2.9 - 5.8范围内相对活性保持在83.2%以上。无论珠子是湿的还是干的，固定在壳聚糖 - 二氧化锆复合珠上的酸性磷酸酶的米氏常数KM和最大反应速率Vmax是固定在纯壳聚糖珠上的1.8倍。在四种固定化酶中，使用湿壳聚糖 - 二氧化锆珠作为载体显示出最低的热失活能（78 kJ mol(-1)）。
