A Study of Preparation Conditions of PVA Capsule and Immobilization of Biocatalyst

研究了聚乙烯醇（PVA）包埋和固定化生物催化剂的最佳制备条件。将具有β-半乳糖苷酶的大肠杆菌的甲苯透化细胞包封在PVA胶囊中，并假设Michaelis-Menten和竞争性抑制动力学来确定酶的动力学性质。Vm的降低是由于酶的失活。固定化酶的Km和Ki均大于游离酶。这种增加可能是胶囊核心中PVA的贡献，因为观察到通过向反应混合物中加入PVA而使游离酶的Km和Ki增加。因此，酶的固定化降低了酶与底物之间的亲和力。制备条件对PVA包埋酶的稳定性有很大影响。这表明蛋白质可以渗透PVA胶囊的膜。酶的产率受制备条件的影响。

The authors investigated optimal preparation conditions of PVA encapsulation and immobilization of biocatalysts. Toluene-permeabilized cells of Escherichia coli having beta-galactosidase was encapsulated in PVA capsule and kinetic properties of the enzyme were determined assuming Michaelis-Menten and competitive inhibition kinetics. The reduction of Vm is due to inactivation of the enzyme. The Km and Ki of the immobilized enzyme were larger than that of the free enzyme. The increases may have been the contribution by PVA in the core of the capsule, because increases in Km and Ki of the free enzyme by addition of PVA into a reaction mixture was observed. Thus, the immobilization of the enzyme reduced the affinity between the enzyme and substrate. The stability of PVA-encapsulated enzyme was considerably affected by the preparation conditions.The recombinant bacteria were immobilized in PVA capsule and enzyme proteins were produced. This indicates that the proteins can permeate the membrane of a PVA capsule. The productivities of the enzyme were affected by the preparation conditions.