Purification of recombinant human growth hormone produced in soluble form in Escherichia coli in lab-scale

Human growth hormone (hGH) or somatotropin is a single chain polypeptid which consisting of 191 amino acid residues and molecular weight of 22kDa. Overexpression of hGH in Cytoplasm often results in forming inclusion bodies (IBs). Purification process of hGH from IBs needs refolding process in order to obtain native protein that is complicated and often does not have good efficiency. Therefore, the high expression of soluble form is always considered.

In this study, recombinant E. coli-pET32a(+)-Trx-His6-hGH was used. In order to obtain high level production of soluble hGH in cytoplasm was used from Trx tag and for purification process of hGH was used from His tag. The bacteria was grown in LB and TB culture media at 25 ⁰C. The purification process carried out based on affinity chromatography using Ni-NTA resin.

The SDS-PAGE analysis showed 55% hGH expression that 33.7% expressed as soluble and 18.8% expressed as IBs. The amount of hGH fusion protein purified through Ni-NTA column was 22. 4 mg per gram of wet cells.

The results of this study indicate that hGH-Trx fusion protein was properly expressed. The purity of hGH fusion protein purified by histidine-tagged protein purification method was determined 91% with the total yield of 38%.