Immobilization of urease via adsorption onto L-histidine-Ni(II) complexed poly(HEMA-MAH) microspheres:: Preparation and characterization
Immobilization of urease via adsorption onto L-histidine-Ni(II) complexed poly(HEMA-MAH) microspheres:: Preparation and characterization
复制标题
DOI：
10.1016/j.procbio.2005.03.058
复制
发表时间：
2005-11-01
影响因子：
4.4
通讯作者：
Arica, MY
中科院分区：
文献类型：
--
作者：
Bayramoglu, G;Yalçin, E;Arica, MY
采用悬浮聚合法制备了聚(2-羟乙基-methacrylate-co-N-methacryloly-L-histidinemethylester))微球。然后，将聚(HEMA-MAH)微球的L-组氨酸基团与镍离子(Poly(HEMA-MAH)-Ni(II))进行络合。在间歇体系中研究了水溶液中尿素酶在聚(HEMA-MAH)和聚(HEMA-MAH)-Ni(II)微球上的固定化。固定化尿素酶在聚(HEMA-MAH)和聚(REMA-MAH)-Ni(II)载体上的固定化量分别为47.8和66.1 mg/g载体。两种固定化尿素酶制剂的米氏常数K-m均显著高于游离酶，表明酶对底物的亲和力降低，而V-max值均小于游离酶。然而，将尿素酶固定在聚(HEMA-MAH)-Ni(II)上后，酶的稳定性随时间的延长而增加。两种固定化制剂的最适操作温度都比游离酶高出5.0℃，而且固定化制剂的温度分布明显更宽。结果表明，酶在聚(HEMA-MAH)和聚(HEMA-MAH)-Ni(II)微球上可以反复吸附和解吸，而不损失吸附容量和酶活性。最后，采用固定化尿素酶的填充床酶反应器，在连续运行模式下对尿素进行降解。该酶反应器在35℃连续运行40h，没有明显的性能损失。(C)2005爱思唯尔有限公司。保留所有权利。
Poly(2-hydroxyethyl methacrylate-co-N-methacryloly-L-histidinemethylester) poly(HEMA-MAH) microspheres was prepared via suspension polymerization. L-Histidine groups of the poly(HEMA-MAH) microspheres were then chelated with Ni(II) ions (poly(HEMA-MAH)-Ni(II)). Urease immobilization onto the poly(HEMA-MAH) and poly(HEMA-MAH)-Ni(II) microspheres from aqueous solutions was investigated in a batch system. The amount of immobilized urease on the poly(HEMA-MAH) and poly(REMA-MAH)-Ni(II) was 47.8 and 66.1 mg/g support, respectively. The values of Michaelis constants K-m for both immobilized urease preparations were significant higher than free enzyme, indicating decreased affinity by the enzyme for its substrate, whereas V-max values were smaller for both immobilized urease preparations compared to free enzyme. However, the urease-immobilized onto the poly(HEMA-MAH)-Ni(II) resulted in an increase in enzyme stability with time. Optimum operational temperature for both immobilized preparations was 5.0 degrees C higher than that of the free enzyme and the temperature profiles of the immobilized preparations were significantly broader. It was observed that enzyme could be repeatedly adsorbed and desorbed on the poly(HEMA-MAH) and poly(HEMA-MAH)-Ni(II) microspheres without loss of adsorption capacity or enzymic activity. Finally, a packed bed enzyme-reactor with/urease-immobilized poly(HEMA-MAH)-Ni(II) microspheres, were used for degradation of urea in the continuous operation mode. The enzyme-reactor operated continuously at 35 degrees C for 40 h without significant loss of performance. (c) 2005 Elsevier Ltd. All rights reserved.