接枝淀粉载体固定化糖化酶的研究

合成了淀粉接枝丙烯腈及丙烯酰胺的两亲性高分子化合物，并以此为载体，用物理吸附方法固定化了糖化酶。最适偶联条件研究表明：缓冲液的浓度，ｐＨ值及吸附时间和加酶量都对固定化酶活力，比活有一定的影响。在最适固定化条件下，固定化酶的活力为１５００Ｕ／ｇ干胶，蛋白载量为２５ｍｇ／ｇ干胶，比活为６０Ｕ／ｍｇ蛋白，比天然酶的比活（８．０Ｕ／ｍｇ蛋白）提高６倍。最适反应温度比天然酶提高１０℃（天然酶最适反应温度为５０℃）．无底物存在下，固定化酶在５５℃的半衰期为２４ｈ，而天然酶只有１ｈ；有底物存在下，固定化酶在５５℃的半衰期为２２０ｈ，４５℃的操作半衰期由外推法算得为６９天，而且该载体对糖化酶有一定的保护作用，当固定化酶在低于５５℃热处理一段时间后，对酶活力有激活作用，酶活力最大可提高４０％。该载体合成简单，固定化方法简单，步骤少，因而为工业上应用提供了一种新的可能性。

The Study of Immobilized Glucoamylase to Grafted Starch Carrier

Glucoamylase was immobilized on the starch-g-PAN-g-PAM by adsorption. The effects of different coupling time, pH of buffer, ionic strength and the amount of GA for immobilization and properties of immobilized glucoamylase were studied. The results showed that the activity of IGA was 1500U/g dry gel. the protein binding capacity was 26mg/g dry gel, the specific activity for IGA was 8 times of that for natural GA. The optimum temperature of IGA was 10 degrees higher than natural GA ( 50 ℃ ) . The half-life-time reached 24 h without substrate at 55 ℃( lh for natural GA) and the operational nalf-life-time reached 220h at 55℃ and 69 days at 45 ℃.