Purified human growth hormone from E. coli is biologically active.

Abstract

Human growth hormone (HGH), somatotropin, is a protein consisting of 191 amino acids with a molecular weight of ∼22,000. It is essential for linear growth and its application in the treatment of hypopituitary dwarfism is well established1–3. Growth hormone may also be effective in the treatment of other disorders including bone fractures, burns and bleeding ulcers4. Because growth hormone is species specific, human cadavers have previously been the only source of HGH. Moreover, the standard purification of pituitary-derived HGH does not provide a homogeneous product, but rather a mixture of native HGH and modified forms and fragments of HGH, each of which may have different physiological roles5. The expression of HGH in Escherichia coli using recombinant DNA technology6 provides an inexhaustible source of a single eukaryotic protein. The bacterially synthesized HGH, produced from E. coli, is methionyl-HGH (Met-somatotropin), the extra methionine arising from the AUG start codon inserted at the beginning of the gene. This cloned product has now been purified to homogeneity and its biological properties examined. For pituitary and bacterially synthesized HGH, specific activities as determined by radioimmunoassay are comparable.