为了克服游离酶在实际工业生产中稳定性不好、活性易丧失、不易回收、重复利用率较低的缺点，对中性蛋白酶进行了固定化研究。将具有磁性的二氧化硅包覆的Fe₃O₄（Fe₃O₄@SiO₂）材料作为载体进行中性蛋白酶固定化实验。考察了交联剂戊二醛的质量分数、交联时间、给酶量、固定化时间、温度和酸碱度对于固定化酶活力的影响，筛选出最佳固定化条件。结果表明，在交联剂质量分数为3%，交联时间为2 h，给酶量为0.20 g/g，固定化时间为3 h的条件下，固定化中性蛋白酶的活性最好。固定化酶的最适温度为50℃，固定化酶的最适pH为7.5，而且一定范围内其热稳定性和pH稳定性都比游离酶有所提高。

In practical industrial applications,the free enzymes have shortages of low operational stability,easily losing activity,difficult recovery and poor reusability.Immobilization of enzymes on solid supports,especially on magnetic materials,can help to overcome these shortages.The immobilization of neutral protease is investigated.The silicon dioxide coated magnetic Fe₃O₄@SiO₂ materials are used as supporter to carry out the immobilization experiments of neutral protease.The influences of the mass concentration of crosslinking agent-glutaraldehyde,crosslinking time,adding amount of enzyme,time for enzyme immobilization,temperature and acidity on the activity of immobilized enzymes are investigated and the best immobilization conditions are screened out.The results show that the best immobilization conditions are as follows:the mass concentration of crosslinking agent is 3%,crosslinking time being 2 hours,the adding amount of enzyme 0.20 g·g^-1,and enzyme immobilization time 3 hours.The most suitable temperature and acidity for enzyme immobilization is 50℃ and pH=7.5 respectively.And thermal stability and pH stability of immobilized enzyme are improved compared with free enzyme within a certain range.

韦克毅(1983-),男,博士,工程师,主要从事烟草化学方面的研究,0871-65031567,keyiwei@126.com。