PRODUCTION OF METHIONYL-MINUS OVINE GROWTH-HORMONE IN ESCHERICHIA-COLI AND ONE-STEP PURIFICATION

The overproduction of ovine growth hormone (oGH) in Escherichia coli is described, achieved in part by alteration of the codon usage for nine of the first 15 amino acids (aa) of the mature hormone. Recombinant oGH (re-oGH), representing 12% of the total cellular protein, was isolated from inclusion bodies by solubilisation using the cationic surfactant cetyltrimethylammonium chloride (CTAC). The hormone was refolded and subsequently purified to greater than 95% homogeneity in a single step using preparative reverse phase high performance liquid chromatography. The aa sequence analysis revealed that the N-terminus of the E. coli-derived polypeptide was identical to that of pituitary-derived oGH, and re-oGH displayed potent somatotropic activity in vivo.