| Biotechnology |
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| Enzymatic synthesis of nucleosides by nucleoside phosphorylase co-expressed in Escherichia coli |
| Qing-bao Ding, Ling Ou, Dong-zhi Wei, Xiao-kun Wei, Yan-mei Xu, Chun-yan Zhang |
| State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China, Shanghai Scibest Biotechnology Co., Ltd., Shanghai 200235, China |
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Abstract Nucleoside phosphorylase is an important enzyme involved in the biosynthesis of nucleosides. In this study, purine nucleoside phosphorylase and pyrimidine nucleoside phosphorylase were co-expressed in Escherichia coli and the intact cells were used as a catalyst for the biosynthesis of nucleosides. For protein induction, lactose was used in place of isopropyl β-D-1-thiogalactopyranoside (IPTG). When the concentration of lactose was above 0.5 mmol/L, the ability to induce protein expression was similar to that of IPTG. We determined that the reaction conditions of four bacterial strains co-expressing these genes (TUD, TAD, DUD, and DAD) were similar for the biosyntheses of 2,6-diaminopurine nucleoside and 2,6-diaminopurine deoxynucleoside. When the substrate concentration was 30 mmol/L and 0.5% of the recombinant bacterial cell volume was used as the catalyst (pH 7.5), a greater than 90% conversion yield was reached after a 2-h incubation at 50 °C. In addition, several other nucleosides and nucleoside derivatives were efficiently synthesized using bacterial strains co-expressing these recombinant enzymes.
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Received: 30 May 2010
Published: 04 November 2010
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