Construction of an Expression Vector for Production and Purification of Human Somatostatin in Escherichia coli

Somatostatin/growth hormone-inhibiting hormone is the peptide that inhibits secretion of somatotropin/growth hormone. Solid-phase synthesis methods are being currently used to produce somatostatin. Recombinant peptide synthesis is widely described for the production of small proteins and peptides; however, the production at industrial scale of peptides for biopharmaceutical applications is limited for economic reasons. Here, we propose the use of a new pGB-SMT plasmid to produce Somatostatin, as a C-terminal fusion protein with a Kluyveromyces lactis beta-galactosidase fragment. To facilitate removal of that fragment by CNBr cleavage, a methionine residue was introduced at the N-terminal of the hormone peptide. The use of this construction enables an IPTG-free expression system. The suitability of this procedure has been assessed in a 15 l scale-up experiment yielding almost 300 mg, with purity > 99 % and it is being implemented for commercial scale. The plasmid pGB-SMT here described is an alternative option for a cheap and high expression of other short peptide hormones.