Production Of Adenine Arabinoside By Microtransformation

Arabinoside adenine (Ara-A) is the Arab sugar-based derivative of adenosine. With a broad-spectrum antiviral activity, it is widely used as antiviral nucleoside drugs in clinical. Synthesis of Ara-A using chemical method are plagued by expensive raw materials, low yields of final product and the formation of undesired by-products. During the last years, biosynthesis of Ara-A has been extensively studied.In this study, Ara-A was synthesied from uridine and adenine using bacterial whole-cell as catalyst.6. kinds of bacterials was screened, and after mutation breeding, a strain of E. aerogenes XHL-222strains for research. After the experiment, optimization of E. aerogenes XHL-222was gained. The fermentation medium was optimized:beef extract1.0%, peptone1.0%,3%yeast extract, glucose0.5%, magnesium sulfate0.03%, NaCl0.5%. The optimal culture conditions for enzyme production:Inoculation volume5%, pH7.2, fermentation temperature32℃, shaking speed210rpm,500mL shake flask containing50mL medium, incubation for21hours. Optimal conversion conditions for the catalytic reaction:temperature55℃, wet cells10%, pH7.2,25mmol/L phosphate buffer, reaction time40h, substrate ratio30mM:30mM. The yield of Ara-A reached about70%.Expand experiment was studied using fermenter. Operational parameters were optimized: seed tank cultured for about10hours before transplanting, add solution of glucose after6h fermentation and adjusted the pH pH at7.2by solution of HCl/NaOH. DO was maintained above50%by controlling the rotational speed and aeration rate.5L conversion reaction was studied, The optimal conditions:rotational speed180rpm, wet cells17%, reaction time40h. Adenine is poorly water-soluble, so it was added to the reaction mixture by continuously feed-batch, flow rate120ml/h. After various adjustments, a yield of74%was reached.Finally, Ara-A was purified using macroporous resin D280column chromatography After recrystallization, a purity of97%was achieved.