Optimization of immobilized metal ion affinity chromatography for single-step purification of recombinant ovine growth hormone expressed in Escherichia coli

In the present investigation, Sepharose 6B gel with 1,4-butanediol diglycidyl ether as spacer arm, iminodiacetic acid as the ligand and Cu2+, Ni2+ as metal ions were used to prepare an immobilized metal ion affinity (IMA) gel. The binding capacities of recombinant ovine growth hormone (roGH) onto IMA gels were maximized in the packed bed column. Parameters influencing the purification efficiencies such as pH, ionic strength and flow-rate were optimized to achieve improved separation. The roGH was purified from inclusion bodies with an overall yield of 73.5% and purity of 94.3% using a Cu2+–iminodiacetic acid (IDA) column. However, the Ni2+–IDA column was more successful in purifying the roGH from crude cell lysate in a single-step with a yield of 83% and purity of 92.5%.