磁性微粒对青霉素G酰化酶的固定化研究

Immobilization of penicillin G amidase by using magnetic microspheres

将无机磁性粒子Fe3O4与有机材料海藻酸钠结合起来制成一种复合的磁性微粒,并将其进行表面修饰,通过化学共价法来固定青霉素G酰化酶。通过扫描电镜等对微粒进行形态学观察,并用傅立叶红外图谱表征微粒表面修饰基团。酶学性质研究表明,该微粒固定化的青霉素G酰化酶的最适pH值为7.5,最适温度为40℃。固定化酶与底物的亲和力有所降低,但是稳定性显著提高。重复催化研究结果表明,固定化酶具有比游离酶更广泛的温度及pH值适用范围,并且具有良好的热稳定性、可循环使用性和贮存稳定性。

The composite magnetic microspheres were synthesized by using Fe3O4 particles encapsuled in surface modified sodium alginate microspheres. The penicillin G amidase （PGA） molecules were immobilized on the surface of the supports through covalent bonds. The morphology of microparticles was studied by SEM, and was characterized by FTIR. The optimal pH value and temperature of the immobilized enzyme are 7.5, 40 ℃, respectively. The substrate affinity of PGA decreases after immobilization. However, the stability of the immobilized enzyme is enhanced. The result of the reuse of immobilized PGA shows that compared with the soluble enzyme, the immobilized enzyme has a more extensive range of temperature and pH value in practical application and the immobilized PGA demonstrates an improved thermal stability, reusability and storage stability.