【作者】 肖宁；

【导师】 马润宇； 王艳辉；

【作者基本信息】 北京化工大学 ， 生物化工， 2005， 硕士

【摘要】 本文以具有较高的比表面、较大孔径及表面富含弱酸性羟基的介孔分子筛MCM—41为载体,戊二醛为交联剂,采用共价交联法固定化木瓜蛋白酶和胰蛋白酶。 首先筛选出木瓜蛋白酶的最适固定化方法,通过对影响固定化木瓜蛋白酶效果的两个因素的研究,筛选出具有最适孔径的载体。以此载体固定化木瓜蛋白酶,优化了固定化条件,结果表明:当每g载体的给酶量为20mg,固定化温度10～20℃,固定化时间2h,pH7.0,戊二醛体积分数0.75%时,木瓜蛋白酶的固定化效果最好,此时平均酶活性回收率达55%左右。 其次,比较了游离酶及固定化酶的催化特性。结果表明:固定化酶的最适pH值为7.5,最适反应温度为75℃;固定化酶对尿素和有机溶剂的稳定性、pH稳定性、热稳定性、贮藏稳定性等与游离酶相比都有显著的提高。并对固定化木瓜蛋白酶的简单动力学常数和固定化酶反应器做了初步探讨,结果表明:固定化酶和游离酶的米氏常数值分别为游离酶3.017g/L,固定化酶0.898g/L;尝试了固定化木瓜蛋白酶填充床反应器,测得固定化酶的操作半衰期为26天。 最后以MCM-41为载体固定化胰蛋白酶,优化了固定化条件,并研究了固定化酶部分催化特性。结果表明:当每g载体的给酶量为30mg,固定化温度15℃,固定化时间3h,pH8.0,戊二醛体积分数0.4%时,胰蛋白酶的固定化效果最好,此时平均酶活性回收率达60%左右。固定化酶的热稳定性、对盐酸胍的稳定性、pH值稳定性与游离酶相比都有了显著的提高,并且固定化酶具有较好的间歇操作稳定性,连续反应10批后,酶剩余活性仍保持在80%以上。更多还原

【Abstract】 Taking advantage of the large pores, high surface area and abundant hydroxyl groups on the surface of mesoporous molecular sieve MCM-41, the immobilization of papain and trypsin using covalent and glutaraldehyde crosslink method on MCM-41 have been studied.Firstly, a better method of immobilization of papain on MCM-41 has been seclected. The carrier that has optimum aperture has been seclected by studying two factors that affect the activity of the immobilized papain. The effects of immobilization conditions on the activity and the activity yield of the immobilized papain have been studied. The results showed that the optimum conditions for immobilization were as follows: the concentration of free enzyme, the concentration of glutaraldehyde, time, temperature and pH for immobilization were 20mg/g, 0.75%, 2h, 10~20℃ and 7.0 respectively. Under the optimum conditions, the activity yield(%) of the immobilized papain was around 55%.Secondly, the characters of these immobilized papain were also studied and compared with native papain. The results showed that the optimum pH value was 7.0, the optimum temperature was 65 ℃; the更多还原