Bacterial Synthesis of Recombinant α-Human Atrial Natriuretic Polypeptide

Publisher Website
Google Scholar
Abstract
The high-level synthesis of α-human atrial natriutetic polypeptide hormone in Escherichia coli has been achieved based on the idea that the yield of a small, basic and unstable polyperptide, such as the natrituretic polypeptide, would be improved by fusion with an appropriate protective polypeptide to construct a neutral fused polypeptide. We prepared an expression vector, pCLaHtrp3t, coding a neutral polypeptide containing 130 amino acid residures in which the polypeptide hormone was fused to a newly designed protective polypeptide through lysine as an enzymatically cleavable residue. The fused polypeptide was synthesized at the high level of 32% of total cellular proteins and at 4.7× 105 molecules sper single cell. It was recovered as cellular insoluble fraction and purified to homogeneity. For the isolation of the peptide hormone from the resultant fused polypeptide, Achromobacter protease I, a lysine-specific endopeptidase was used, because it has sufficient activity even in 8 M urea. The recombinant natriuretic polypeptide was indistinguishable from native α-human atrial natriuretic polypeptide as regards amino acid sequence as well as biological activity.