Purification and characterization of recombinant bovine growth hormone produced in Escherichia coli

Using the pUBJ10 plasmid containing the modified bovine growth hormone (bGH) cDNA, large production has been attempted in E. coli BL21 strain. The bGH was highly expressed upto the level of 35% of total cell proteins by IPTG induction and temperature shift to 40°C. The recombinant bGH (rbGH) was isolated from inclusion bodies by solubilization in 10 M urea and followed by DEAE-TOYOPEARL 650C ion exchange and Sephadex G-100 column chromatography. The pUBJ10-derived bGH was eluted at 25.28 min similar to the standard bGH (at 25.18 min) by reverse-phase HPLC. The analysis of N-terminal amino acid showed that the mature bGH has glutamic acid as a first amino acid in agreement with DNA sequencing data. The biological activity was indirectly measured by radioreceptor assay and compared with a pituitary-derived bGH.