Process for the Purification of Recombinant Granulocyte-Colony Stimulating Factor

The present invention describes a novel process for large scale purification of therapeutic grade quality of recombinant human G-CSF from microbial cells, wherein the protein is expressed as inclusion bodies. The process involves the novel use of Hydrophobic Interaction Chromatography (HIC) step to purify G-CSF eluted from a cation exchange column. A combination of these two chromatography steps provides good purity and yields which are essential for a production scale process. The host cell related contaminants like proteins, DNA and endotoxins are estimated to be within the specifications outlined by the drug regulatory authorities.