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文档编号:SW027 文档字数:11319,页数:23 摘要：本文首先介绍了固定化酶的定义，制备方法和性质。在实际应用中，利用游离酶作为催化剂有很多局限性，因此本文主要研究脂肪酶的固定化。首先用磁性纳米材料与3-氨基丙基三乙氧基硅烷相结合，得到的产物再用戊二醛试剂以共价键与脂肪酶相结合。脂肪酶能够高选择性的催化手性化合物，因此以外消旋2-溴丙酸，2-氯丙酸和2-溴已酸转酯化反应作为模型反应，考察磁性纳米固定化脂肪酶催化的效果。反应方程式如下： 分离R-羧酸正丁酯转化率在76%和80%之间和S-羧酸转化率在78%和82%之间，R-羧酸正丁酯和S-羧酸的ee值都高达99%。又以外消旋2-溴丙酸为模型反应考察磁性纳米固定化脂肪酶的重复使用情况，经过4轮反应，转化率从29%降到20%，而游离酶转化率从第一轮的55%到第二轮下降到7%，在第三、第四轮反应中游离酶完全丧失了催化活性。 关键词：磁性纳米；脂肪酶；固定化；酯化
Abstract: The content of immobilization of enzyme was introduced ,including conceptions，preparation methods and properties .There are many limitations in application of free enzyme. So in this paper, immobilization of lipase was studied. Superparamagnetic nanoparticles were first immobilized with 3-aminopropyltriethoxysilane.Then glutaraldehyde was employed as a linker to the lipase to the surface of nanoparticles to form Iron Oxide-lipase. The lipase can catalyze the chiral resolution with high selectivity. To determine the effection of immobilization, the selectively transesterification of racemic 2-bromopropionic acid, 2-chlorinpropionic acid, 2-bromocaproic acid was taken as model reaction. The reaction equation was as follows: Average isolation yields of 76% and 80% ware obtained for R-butyl esters and the yields of 78% and 82% ware obtained for S-carboxylates, respectively. The ee value of isolated R-butyl esters and S-carboxylates were usually higher than 99%. In a typical experiment, to determine the possibility of recycling the nanoparticle-supported lipase for repeated uses, racemic 2-bromopropionic acid was chosen as model reaction. The conversion percentages dropped from 29% to 20% after four reaction cycles for Iron Oxide-lipase. In comparison, the free lipase demonstrated much higher enzymatic activity with a conversion yield of 55% in the first round reaction. However, the catalytic activity of the free enzyme decreased rapidly from 55% to 7% in the second reaction cycle. It completely lost its enzymatic activity in its third and fourth rounds of reaction. 目录
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| Tags：磁性 纳米 固定化 脂肪 研究 | 2011-03-31 13:30:23【返回顶部】 |
