壳聚糖-Fe_3O_4超顺磁微球固定脂肪酶催化拆分(R,S)-1-苯乙醇

Lipase Immobilized on Chitosan-Fe_3O_4 Microspheres for Catalyzing the Transesterification Resolution of(R,S)-1-Phenylethanol

为将脂肪酶固定化,以提高酶的稳定性、使酶可以重复利用和降低生产成本,采用化学共沉淀法制备Fe3O4,以透射电镜、X-射线粉末衍射和红外光谱对所得产品进行表征,并且采用硅烷-戊二醛偶联法和壳聚糖包埋法分别将脂肪酶固定于磁球表面,再以生物拆分(R,S)-1-苯乙醇为模型考察了各种因素对转酯反应的影响。结果表明:化学共沉淀法制备Fe3O4为粒径小于20 nm的磁性纳米粒子;壳聚糖包埋法操作简单、酶载量大;扫描电镜分析揭示固定酶的磁球表面含有大量微孔结构。在最佳条件下,1-苯乙醇的转化率达44.3%,对映体过量值eep为99%,酶的半衰期为121h。反应完成后,施加外磁场可使酶与反应体系迅速分离,固定化酶重复使用11次酶的活性没有明显减少,说明壳聚糖-Fe3O4超顺磁微球固定脂肪酶具有高的活性和稳定性。

Immobilization of enzyme can improve the thermal stability and reusability, and reduce production cost. The Fe304 nanoparticles were obtained by the co-precipitation method, characterized by transmission electron microscope, X-ray diffraction and fourier transform infrared spectroscopy. Two methods for immobilizing enzyme including cross-linking on ~/-aminopropyltriethoxysilane functionalized Fe304 using glutaraldehyde as a coupling agent and embedding method, were investigated in this study. Then the transesterification reaction of （R, S）-1-phenylethanol was employed as a model to investigate the effect various factors on the reaction. The particles size is less than 20 nm. The latter method was employed due to its simplicity in use and relatively big loading capacity of the enzyme. The scanning electron microscope revealed there are very abundant mieropore on the surface of the Fe3Q magnetic nanoparticles embedded enzyme. Under optimal condition, 1-phenylethyl conversion, ee value of （R）-l-phenylethyl acetate and half life time of the lipase were 44.3 %, 99% and 121 h, respectively. After the completion of thereaction, the enzyme was rapidly separated from the reaction system using an external magnetic field. It was found that the enzyme activity remained almost unchanged when it was reused for 11 times. These results indicated that the lipase of high activity and stability. embedded by chitosan-Fe304 magnetic microspheres is