Arica M Y, Hasirci V
Department of Biological Sciences, Middle East Technical University, Ankara, Turkey.
J Chem Technol Biotechnol. 1993;58(3):287-92. doi: 10.1002/jctb.280580313.
Glucose oxidase was immobilized onto poly(2-hydroxyethyl methacrylate) (pHEMA) membranes by two methods: by covalent bonding through epichlorohydrin and by entrapment between pHEMA membranes. The highest immobilization efficiency was found to be 17.4% and 93.7% for the covalent bonding and entrapment, respectively. The Km values were 5.9 mmol dm-3, 8.8 mmol dm-3 and 12.4 mmol dm-3 for free, bound and entrapped enzyme, respectively. The Vmax values were 0.071 mmol dm-3 min-1, 0.067 mmol dm-3 min-1 and 0.056 mmol dm-3 min-1 for free, bound and entrapped enzyme. When the medium was saturated with oxygen, Km was not significantly altered but Vmax was. The optimum pH values for the free, covalently-bound and entrapped enzyme were determined to be 5, 6, and 7, respectively. The optimum temperature was 30 degrees C for free or covalently-bound enzyme but 35 degrees C for entrapped enzyme. The deactivation constant for bound enzyme was determined as 1.7 x 10(-4) min-1 and 6.9 x 10(-4) min-1 for the entrapped enzyme.
葡萄糖氧化酶通过两种方法固定在聚甲基丙烯酸2-羟乙酯（pHEMA）膜上：通过环氧氯丙烷进行共价键合以及包埋在pHEMA膜之间。共价键合和包埋的固定化效率最高分别为17.4%和93.7%。游离酶、键合酶和包埋酶的米氏常数（Km值）分别为5.9 mmol dm-3、8.8 mmol dm-3和12.4 mmol dm-3。游离酶、键合酶和包埋酶的最大反应速率（Vmax值）分别为0.071 mmol dm-3 min-1、0.067 mmol dm-3 min-1和0.056 mmol dm-3 min-1。当介质中的氧气饱和时，Km没有显著变化，但Vmax发生了变化。游离酶、共价键合酶和包埋酶的最适pH值分别确定为5、6和7。游离酶或共价键合酶的最适温度为30℃，而包埋酶的最适温度为35℃。键合酶的失活常数确定为1.7×10(-4) min-1，包埋酶的失活常数为6.9×10(-4) min-1。
