交联糖化酶聚合体的制备与性质研究

Study on Preparation and Characters of Cross-Linked Glucoamylase Aggregate

交联糖化酶聚合体是利用硫酸铵沉淀糖化酶,以戊二醛为交联剂对其进行化学交联,制备出的一种无载体固定化糖化酶。本实验对交联糖化酶聚合体的制备和酶学性质进行研究。实验结果表明:交联酶聚合体的最终酶活力为3.15×104U/g干胶,其作用的最适pH4.6,最适反应温度为50℃,Km值为1.75%,当酶保护剂黄原胶的添加量为5.0mg/g时,交联糖化酶聚合体残余酶活力较高,且具有比游离酶更高的热稳定性。

The free glucoamylase in the 0.05 mol/L acetate-sodium acetate buffer（pH 4：6） was precipitated by ammonium sulfate and then cross-linked by glutaraldehyde to prepare glucoanylase aggregate, which is a carrier-free immobilized enzyme. The preparation process and the enzymatic characters of cross-linked glucoamylase aggregate were studied. Results showed that the final activity of the eross-linked glucoarnylase aggregate is 3.15×10^4 U/g （dry）. The optimum pH and reaction temperature as well as Km of the cross-linked glucoamylase aggregate are 4.6, 50 ℃ and 1.75% respectively. As the content of xanthan gum is 5.0 mg/g（free glucoamylase）, the residual activity and thermostability of the cross-linked glucoamylase aggregate are both higher than the free glucoamylase.