具有谷氨酸脱羧酶的大肠杆菌固定化细胞

本文研究了用海藻酸钙包埋法制备含谷氨酸脱羧酶固定化细胞的方法以及研究了制备的条件和影响其制备的因素。该法具有包埋细胞活力回收高,方法简便等优点。比较研究了固定化细胞和自然细胞谷氨酸脱羧酶的一些生物化学性质。其中固定化细胞最适pH和pH稳定性增加,最适温度及热稳定性下降;表观米氏常数增大;二价金属离子Zn~(++)、Cu~(++)、Mg~(++)、Fe~(++),Sr~(++)程度不同的抑制酶活性,Ca~(++)激活固定化细胞酶活性,EDTA无抑制作用。对固定化细胞和自然细胞酶活力活化的研究中发现这两种细胞经蒸馏水保温处理后酶活性都上升,且自然细胞酶活的上升较固定化细胞大;而用底物溶液处理后,自然细胞无变化,固定化细胞酶活下降。

THE IMMOBILIZED CELLS OF ESCHERICHIA COLI POSSESSING GLUTAMATE DECARBOXYLASE ACTIVITY

1. Escherichia coli (E.coli) cells possessing glutamate decarboxylase activity have been immobilized by entrapping the cells in calcuim alginate gel lattice followed by Cros-Linking with glutardialdehyde. A considerable amount of the cells could be immobilized into the gel by this method and the resulting immobilized cells had high enzyme activity and enough mechanical strength. Also, the process was simple.2. The optimum conditions for immobilization with calcuim alginate were studied. It was found that different conditions affected obviously the enzymes activity of the immobilized cells.3. The enzymatic properties of immobilized E. coli cells were studied and compared with those of native cells. The glutamate decarboxylase of the immobilized cells exhibited an increase in the apparent Michaelis constant (K'm), optimum pH, pH stability. But decrease in the optimum temperature and heat stability. It was proved that bivalent metal ions such as Zn+ + , Cu ++, Mg + +,Fe + +, Sr++, inhibited emzymatic activiy in both kinds of cells. But Ca++ actived emzyme in immobilized cells.4. The glutamate decarboxylase activity of these two kinds of cells increased during incubation in a distilled water at 37℃, and that of the native cells was more than that of immobilized cells the glutamate decarboxylase activity of native cells were not changed, and that of immobilized cells decreased during incubation in a solution of 0.05mol/L glutamate at 37℃.