新型树枝状分子复合载体的合成及其对脂肪酶的固定化

Preparation of Dendritic Silica Composite Carriers and Immobilization of Lipase Thereon

合成了5种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)05G′型复合载体上氨基的含量最高(1646mmol/g),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(15G>05G;20G>10G),(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(05G和15G经水解改性后,活力分别比水解前提高354%和131%)。经测定,固定化酶的最适温度为40℃,pH=75。最佳的固定化条件为搅拌时间为30min,加酶量为75mg/g(以载体计)。

Five dendritic composite silica carriers were prepared and tested in immobilization of porcine pancreas lipase(PPL). The experimental results showed that the content of amino groups 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 showed the best efficiency in immobilizing PPL mainly due to its highest content(1 646 mmol/g) of amino 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 improved by 35 4% and 13 1%, respectively, when the carriers 0 5G and 1 5G were modified by hydrolysis, indicating that the carboxyl groups on the surface of the carrier favor the immobilization of lipase to the ester groups. The lipase immobilized on 0 5G′ composite carrier showed the best activity at 40 ℃ and in the buffer of pH 7 5. The immobilization conditions were optimized, and the best stirring time was 30 min , and the optimal mass ratio of carrier to lipase about 1 000∶75.