Optimization of refolding with simultaneous purification of recombinant human granulocyte colony-stimulating factor from Escherichia coli by immobilized metal ion affinity chromatography

Immobilized metal ion affinity chromatography (IMAC) is a new technique for protein refolding, but it is limited to the refolding of fusion proteins with histidine affinity tags. In the present work, a non-fusion recombinant protein, recombinant human granulocyte colony-stimulating factor (rhG-CSF) expressed in Escheriachia coli (E. coli) in the form of inclusion bodies was successfully refolded with simultaneous purification by IMAC. rhG-CSF inclusion bodies solubilized in 8.0 mol/L urea was injected into a Cu(II)-iminodiacetic acid (IDA)-IMAC column, the soluble and active form of rhG-CSF in aqueous solution was obtained after desorbed from the column by linear increase of imidazole concentration. Several factors in the refolding process, including urea concentration and pH of mobile phases, type of buffer, glycerol concentration and loading sample volume, were investigated, respectively. When 200 μL of denatured/reduced rhG-CSF solution at a total protein concentration of 2.8 mg/mL was loaded on the IMAC column, rhG-CSF with a specific activity of 2.3 × 108 IU/mg and a mass recovery of 39% was obtained after IMAC refolding, and rhG-CSF was also purified during this chromatographic process, its purity was determined to be 97%.