海藻酸钠-阿拉伯胶固定化酸性蛋白酶及其性质的研究

以海藻酸钠（SA）与阿拉伯胶（GA）为载体固定化酸性蛋白酶，以酶活回收率为评价指标，在单因素试验基础上，通过正交试验优化固定化条件。得到以SA-AG复合凝胶为载体制备固定化酸性蛋白酶的最佳工艺条件为：复合凝胶质量浓度3.5 g/100 mL，SA与AG质量比2∶1，氯化钙质量浓度7.0 g/100 mL，固定化时间1.0 h，给酶量1 540 U/g，吸附时间2.0 h，酶液pH值为3.0。此最佳条件下，固定化酸性蛋白酶酶活回收率为67.34%，酶活力为1 380 U/g。固定化酶酶学性质的研究结果表明，固定化酸性蛋白酶的最适作用温度（45 ℃）和最适反应pH值（pH=3）均与游离酶相同，但其热稳定性优于游离酶，且随着温度的升高这种优势越明显。

Immobilization of acid protease with sodium alginate - Arabic gum and study of protease properties

Using the sodium alginate (SA) and Arabic gum (AG) as carrier to immobilize acid protease, and using enzyme activity recovery rate as the evaluation index, the immobilization conditions were optimized by orthogonal experiments on the basis of single factor experiments. The result s showed that the optimum technological conditions of acid protease immobilization with SA-AG composite gel as the carrier were composite gel content 3.5 g/100 ml, SA-AG mass ratio 2∶1, calcium chloride content 7.0 g/100 ml, immobilization time 1.0 h, enzyme addition 1 540 U/g, adsorption time 2.0 h, pH of enzyme liquid 3.0. Under the conditions, the recovery rate of immobilized acid protease activity was 67.34%, and enzyme activity 1 380 U/g. The research results of immobilized enzyme properties showed that the optimal temperature (45 ℃) and the optimal pH (3.0) of immobilized acid protease were the same as the free enzyme. The thermal stability of immobilized acid protease was better than that of the free enzyme, and this advantage was more and more obvious with the increase of temperature.