Enzyme leakage can be reduced to minimum[186]. However, the enzyme may be Deactivated by the chemical modification.Discrepancies in the nature of the active Functionality,for example size,charge,and polarity might influence the nature of The binding,for example binding position and humber of bonds formed between The enzyme and the carriers. Studies have revealed that the nature if inert functionalitu also has a large effect On enzyme activity and stability.For instance,the activity of enzymeentrapped in a gel matrix formed by a sol-gel process depends largely on the nature of the pre- cursor,namely the side chains,suggesting the interaction of the enzyme moletion or orientation[204]. 4.3.2.2 Aquaphilicity of the carriers Like other types of immobilized enzyme,the hydrophilicity of the matrix of the en- Trapped enzyme has also large effect on enzyme activity,stability,and selectivity.A Systematic study on effect of aquaphilicity is,however,still lacking,because it is Very difficult to obtain a set of matrices with variable aquaphilicity. Interestingly,this was beautifully demonstrated by the observation that the rations Of the two polymers used for immobilizing enzymes such as invertase and glucose Isomerase, and yeast cells,in PEC-HEA/PPG-HEA dictated the activity of the Entrapped biocatalysts,suggesting that the aquaphilicity dose have great influence On the enzyme activity[60]. In the same way as for lipase covalently immobilized on hydrophobic carriers.lipase Entrapped in a hydrophobic matrix also displayed preference for the hydrophobic Matrix with regard to retention of activity[77]. 4.4 Effect of Entrapment Depending on the method selected,the matrix formed also has a substantial effect on the performance of the immobilized enzymes,for example activity,selectivity, and stability.Thus,it is essential to select the appropriate method,according to the peculiarities of each enzyme and application. 4.4.1 Atcivity of the Entrapped Enzyme Retention of activitu of the immobilized enzymes is a dimensionless quantity and Denotes usually the ratio of the specific activity fo the immobilized enzyme (U mg-1 protein immobilized)to that of the free enzyme(U mg-1 portein). This term is only valid when the activity of the free enzyme and the immobilized Enzyme are measured in the same reaction and medium.When the free enzyme is In lyophilized form or dissolved in aqueous solution.酶泄漏可降至最低[ 186 ] 。然而，酶可解除化学modification.Discrepancies性质的积极功能，例如大小，费用，而且极可能影响的性质，有约束力的，例如有约束力的地位和亨伯债券之间形成酶和运营商。研究表明，如果惰性的性质functionalitu也有很大影响对酶活性和stability.For例如，在活动的enzymeentrapped凝胶基质形成的溶胶凝胶法在很大程度上取决于的性质预先光标，即侧链，表明酶的相互作用moletion或方向[ 204 ] 。4.3.2.2 Aquaphilicity运营商像其他类型的固定化酶，亲水的矩阵恩被困酶也很大影响酶活性，稳定性和selectivity.A系统影响的研究aquaphilicity但是，仍然缺乏，因为它是很难获得一套矩阵变aquaphilicity 。有趣的是，这是美丽的观测表明，该口粮两聚合物用于固定酶，如蔗糖，葡萄糖异构酶和酵母细胞，在PEC-HEA/PPG-HEA决定的活动包埋生物催化剂，这表明aquaphilicity剂量有很大影响对酶活性[ 60 ] 。以同样的方式为共价固定化脂肪酶的疏水carriers.lipase包埋在疏水基还显示倾向于疏水矩阵关于保留活动[ 77 ] 。4.4影响圈套根据选定的方法，形成的矩阵也有重大影响对业绩的固定化酶，例如活性，选择性，和stability.Thus ，必须选择适当的方法，根据每个酶特性与应用。4.4.1 Atcivity酶的包埋保留activitu的固定化酶是一个无量纲的数量和是指通常的比例的具体活动的固定化酶（ ü毫克- 1蛋白固定化）这一自由酶（ ü毫克- 1 portein ） 。这个词是唯一有效的活动自由酶和固定化酶是衡量同样的反应和medium.When免费酶在冻干形式或溶解在水溶液中。