中文摘要：

构建了一株能高效表达嘌呤核苷磷酸化酶（PNPase）的重组大肠埃希菌Escherichia coli BL21（pET-His-pup G）。选择不同包埋剂进行细菌细胞固定化,结果显示明胶的包埋效果较好。进一步确定明胶包埋细胞的最适反应条件：温度55℃,菌体包埋浓度200 g/L,固定化细胞用量20 g/L,催化周期20 h。在pH 7.6的磷酸盐缓冲液中,底物鸟苷和1,2,4-三唑-3-甲酰胺（TCA）浓度均为100 mmol/L,采用上述固定化细胞催化合成利巴韦林,连续反应8次后,固定化细胞仍具有较高的酶活力。

英文摘要：

A recombinant Escherichia coli BL21 （pET-His-pupG） was constructed to express purine nucleoside phosphorylase （PNPase） efficiently. In this study, the cell immobilization experiment was conducted using different entrapment agents. The results revealed that the gelatin was the best entrapment agent for cell immobilization. Furthermore, the optimal catalytic conditions for cell immobilization were determinated as follows： the reaction temperature of 55 ℃, the entrapped cell concentration of 200 g/L, the immobilized cell dosage of 20 g/L and the reaction period of 20 h. The synthesis of ribavirin was carried out by immobilized cell with 100 mmol/L guanosine and 100 mmol/L 1,2,4-triazole-3-carboxamide （TCA） as substrates in phosphate buffer （pH 7.6）. The immobilized cell was stable with high enzymatic activity after 8 batches of consecutive reaction.