磁性納米固定化脂肪酶研究

生物工程論文編號:SW027  論文字數(shù):11319,頁數(shù):23

目錄
中文摘要 I
英文摘要 II
目錄 Ⅲ
1. 緒論 1
 1.1 脂肪酶的概述 1
 1.2 酶的固定化 1
 1.3 脂肪酶固定化研究進展 6
 1.4 本文思路 7
2. 實驗部分 9
 2.1 實驗材料 9
 2.2 實驗方法 10
3. 結(jié)果與討論 13
 3.1 磁性納米固定化脂肪蛋白含量的測定 13
 3.2 磁性納米固定化脂肪酶轉(zhuǎn)酯反應(yīng)的結(jié)果  13
 3.3 磁性納米固定化脂肪酶重復(fù)使用的情況 14
4．總結(jié)與展望 15
致謝 17
參考文獻 18

摘要：本文首先介紹了固定化酶的定義，制備方法和性質(zhì)。在實際應(yīng)用中，利用游離酶作為催化劑有很多局限性，因此本文主要研究脂肪酶的固定化。首先用磁性納米材料與3-氨基丙基三乙氧基硅烷相結(jié)合，得到的產(chǎn)物再用戊二醛試劑以共價鍵與脂肪酶相結(jié)合。脂肪酶能夠高選擇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-溴已酸轉(zhuǎn)酯化反應(yīng)作為模型反應(yīng)，考察磁性納米固定化脂肪酶催化的效果。反應(yīng)方程式如下：

分離R-羧酸正丁酯轉(zhuǎn)化率在76%和80%之間和S-羧酸轉(zhuǎn)化率在78%和82%之間，R-羧酸正丁酯和S-羧酸的ee值都高達99%。又以外消旋2-溴丙酸為模型反應(yīng)考察磁性納米固定化脂肪酶的重復(fù)使用情況，經(jīng)過4輪反應(yīng)，轉(zhuǎn)化率從29%降到20%，而游離酶轉(zhuǎn)化率從第一輪的55%到第二輪下降到7%，在第三、第四輪反應(yīng)中游離酶完全喪失了催化活性。

關(guān)鍵詞：磁性納米；脂肪酶；固定化；酯化

The study of superparamagnetic nanoparticle-supported lipase

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.
Keywords：Superparamagnetic nanoparticles; lipase; immobilization; transesterification