论文标题:树枝状分子复合载体的合成及其对酶的固定化研究
Preparation of Dendritic Composite Carriers and Their Application in the Immobilization of Enzymes
论文作者 邓彩
论文导师 龚跃法,论文学位 硕士,论文专业 无机化学
论文单位 华中科技大学,点击次数 104,论文页数 66页File Size802k
2004-05-01论文网 http://www.lw23.com/lunwen_2886152/ 脂肪酶; 漆酶; 树枝状分子复合载体; 固定化; 生物催化
porcine pancreas lipase; laccase; dendritic composite silica carrier; immobilization; biocatalysis
酶是一种生物催化剂,游离酶存在的缺点已经不能适应现代工业生产的需要,固定化材料的选择是固定化酶研究的重点。树枝状高分子是一种人工合成的新型材料,近20年来,以其独特的结构和性能在材料科学到生物医学等诸多领域中都受到了日益广泛的关注。本论文首先合成了一系列新型的酰胺-胺型树枝状分子复合二氧化硅载体,研究了它们对脂肪酶PPL的固定化效果。结果表明:载体上氨基的含量、树枝链的长度、表面基团的性质等因素对酶的固定化效率和固定化酶的相对活力都有较大的影响,其中(1)0.5G(型复合载体上氨基的含量最高(1.646mmol/g),其对酶的固定化效果最好,(2)树枝链增长,酶的固定化效率和固定化酶的相对活力增大(1.5G(0.5G;2.0G(1.0G),(3)表面含有羧基的复合载体对酶的固定化效果明显大于表面含有酯基的复合载体(0.5G、1.5G、2.5G经水解改性后,活力分别比水解前提高35.4%、13.1%和52.3 %)。经测定,固定化酶的最适温度为40(C,pH为7.5。最佳的固定化条件为:搅拌时间为30min,加酶量为75mg/g载体。其次,利用0.5G(和1.0G型载体对漆酶进行了固定化。发现用0.5G(型载体固定化漆酶时,最佳固定化条件为:缓冲溶液的pH值为6.5(游离酶为7.4),离子浓度为25mmol/L,吸附时间为10h。对1.0G型载体,最佳的离子浓度也为25mmol/L。对比实验表明:0.5G(型载体优于1.0G型载体。由此可见,本文合成的树枝状分子复合二氧化硅载体是一类性能良好的酶固定化材料。这类载体为系统研究载体表面基团的性质对酶固定化效果的影响规律提供了一个有用的平台。
As a biocatalyst, free enzyme’s defect can’t meet with the requirement of modern industry. So it’s important to develop a new kind of material which can immobilize the free enzyme efficiently. Dendrimers are recognized as a new class of synthetic material,which have been applied in life science and material science because of their unique structure and property.In this work a series of dendritic composite silica carriers was newly prepared, and used firstly for the immobilization of porcine pancreas lipase. The experimental results clearly show that the content of amino groups distributed on the carrier surface, the chain length and the properties of organic groups have important influence on immobilization efficiency of PPL and the relative activity of immobilized lipase. Among all the carriers, 0.5G( composite carrier has the best efficiency to immobilize PPL mainly due to its highest content (1.646 mmol/g) of basic group on the surface. The activity of immobilized lipase is obviously raised with the increase of the organic chain length and the content of amino group (1.5G(0.5G; 2.0G(1.0G). The activity of immobilized lipase improves respectively in 35.4%、13.1% and 52.3 % after the carriers 0.5G、1.5G and 2.5G are modified by hydrolysis, indicating that the distribution of carboxyl group on the surface of carrier favors the immobilization of lipase in comparison with that of the ester group. The lipase immobilized on 0.5G( composite carrier shows the best activity at 40 oC and in the buffer of pH 7.5. The immobilization conditions are optimized, and found that the best stirring time is 30 min, and the optimal ratio of carrier to lipase about 75mg/g carrier.Moreover, 0.5G( and 1.0G composite carriers have also been used for the immobilization of laccase. The laccase immobilized on 0.5G( composite carrier shows the best activity in the buffer of pH 6.5 (free enzyme is 7.4), ion concentration is 25 mmol/L, stirring time is 10h For 1.0G composite carrier, the optimal ion concentration also is 25 mmol/L. All the results demonstrate that the dendritic composite silica carrier is a kind of valuable immobilization carrier. It provides us a useful platform for investigating how the properties of surface groups on the carriers to affect the immobilization efficiency of enzymes.
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