磁性纳米粒子的制备及脂肪酶的固定化

建立了以纳米级磁性粒子为载体固定化脂肪酶的方法，优化了脂肪酶的固定化条件，考察了固定化酶的性质. 制备的磁性载体平均粒径20 nm，具有超顺磁性，分散和再分散效果好. 固定化酶的最适吸附时间为60 min，酶用量:载体量为1:1，固定化酶的酶活达到718 U/g. 结果表明，经纳米磁性粒子固定化后，脂肪酶得到活化，固定化酶比活为游离酶的1.8倍. 同时，固定化脂肪酶的pH稳定性显著提高.

Preparation of Magnetic Nanoparticles and Its Application to Enzyme Immobilization

Lauric acid-stabilized magnetic nanoparticles were prepared and used for enzyme immobilization. The Fe3O4 magnetic nanoparticles were characterized by transmission electron microscopy and magnetic measurements. The observations indicated that the particles were superparamagnetic. Magnetic sedimentation of the nanoparticles was achieved within 0.6 min in organic solution, 200 times faster than the gravitational sedimentation. Lauric acid provided a hydrophobic interface to the immobilized lipase, and the conformational changes induced by interacting with the hydrophobic interface yielded an "open structure" of the lipase. CRL was immobilized to the magnetic carrier with a specific activity of 718 U/g, 1.8 times higher than the free lipase containing the same protein quantity. The pH dependencies of the immobilized and free lipases were investigated and the optimum pH for them were determined. Moreover, activity amelioration and stability of the immobilized lipase for the hydrolysis of olive oil was observed.