Fermentation And Purification Of The Fusion Protein Of Human Serum Album/Interleukin-11

Human interleukin-11(IL-11) is an important factor in hematopoietic system and generating thromboiesis.In order to prolong the half-life,the recombinant plasmid which includes the encoding gene of HSA-IL-11 was constructed,and successfully expressed in Pichia pastoris GS115,but with the problem of the low level expression and high degratatiom there is no more potential in this transformant.The research construct an immunology method to sreening the high-level expressing transformants of HSA fusion protein and then screening 2 differnet kinds of hosts,they were P. pastoris GS115 and P. pastoris SMD1168.It can be showed that the best expressing host was P. pastoris GS115, the concerntration of HSA-IL-11 is 178 mg/L and during the optimized procession it can be up to 220 mg/L.Discussed the different nitrogen of fermentation medium,the different fed-way of methol,the different pH,the different temprature during the expressing in 5 L fermenter.Finally determined the technology as:choose the organic nitrogen medium,the induced pH with 6.0,lower the induced temprature to 20℃and the degratation was eased well.Finally discovered the purification conditions of HSA-IL-11, we've developed the preliminary technology of purification. A new purification process includes Blue Sepharose fast flow, Octyl Sephrose fast flow and Sp Sepharose fast flow after ultrafiltration.A high purity fusion protein will be get after the process,and the recovery will reach 17%.The activity of HSA-IL-11 was 1.15×105 AU/mg.