产青霉素酰化酶的大肠杆菌AS1.76的固定化

IMMOBILIZATION OF PENICILLIN ACYLASE-PRODUCING ESCHERICHIA COLI AS 1.76

用在有机溶剂中成型的琼脂凝胶包埋,结合戊二醛处理的方法,制备产青霉素酰化酶的大肠杆菌AS1.76固定化细胞,其细胞含量可达50%以上。固定化细胞水解青霉素 G 钾盐的最适 pH 为8.0,比原细胞约高0.3pH 单位;最适温度与原细胞一样,均为45℃。固定化后,Hg2+对酶抑制作用降低,但酶对Fe3+、Cu2+等金属离子敏感性增加。在无底物情况下,与原细胞相比,固定化细胞对 pH 和热的稳定性增加;4℃保存14个月无活力损失。固定化细胞装柱,在pH7.7,37℃下连续裂解青霉素 G,转化率达95%以上。155天无明显酶活力损失。

The immobilized cells of Echerichiacoli AS 1.76 with high activity of peni-cillin acylase were prepared by entrapping40—60% bacterial cells in 4% agar gelbeads formed in stirring organic solventand crosslinked with 0.5—1.0% glutaralde-hyde solution.The optimum pH for thehydrolysis of benzylpenieillin by the im-mobilized cells was found to be pH 8.0,while that of native cells was pH 7.7.Theoptimum temperature of the immobilizedcells was the same as that of the nativecells,40℃.The inhibition of the im-mobilized cells by Hg2+ was found to beless than that of the native cells,whilethe sensitivity of the immobilized cells to-ward metallic ions such as Fe3+ and Cu2+etc.slighly increased.The stability of theimmobilized cells to variation of pH andtemperature was higher than that of thenative cells.No loss of activity was ob-served upon storage at 4℃ for 14 months.When the immobilized cells were packedin the column and fed continuously with2% benzylpenieillin solution at 37℃ andpH 7.7,the initial activity remained un-changed after 155 days.