Purification of Recombinant Human Interleukin-3 from Bacillus Licheniformis

For the production of a protein by means of recombinant DNA technology, Gist-brocades has developed the so called PLUGBUG system. This system was applied for the production of Human Interleukin-3 (hIL-3) as a pharmaceutical protein. The gene for the native protein was cloned in Bacillus Licheniformis which is one of our hostcell expression systems of procaryotic origin. For the isolation of hIL-3 from the cell free filtrate, a purification process was developed. This process consists of 4 different column steps and starts with hydrophobic interaction chromatography on Fractogel TSK butyl 650C. By this step hIL-3 was concentrated and separated from most of the contaminating proteins. Next the procedure was further extended with two different steps of ion exchange chromatography on Q-Sepharose Fast Flow resulting in a preparation that was free from contaminating proteins (including hIL-3 degradation products) as well as DNA and endotoxins. For the removal of some aggregates, gelfiltration on Sephacryl S100 HR was chosen as the final step, resulting in a pure and highly active endproduct.