Characterization and Expression Profiling of Recombinant Parathyroid Hormone (rhPTH) Analog 1–34 in Escherichia coli, Precise with Enhanced Biological Activity

Abstract

Human truncated parathyroid hormone [hPTH (1–34)], a peptide hormone which accelerated the research interest towards the theraputical applications. This study outlines the effective expression of [hPTH (1–34)] in Escherichia coli and the recuperation of highly soluble truncated PTH from the fusion protein by proteolytic digestion. Successful expression of glutathione S-transferase (GST) fusion protein was achieved by incorporating truncated PTH with an enzymatic cleavage site into the “N” terminal GST of pGEX-4T-3 expression vector. Under the optimized condition, we achieved more than 120 mg of pure hPTH (1–34) per liter of bacterial culture, with an overall yield of 39%. Purification process was carried out through immobilized metal ion chromatography and membrane filter to produce maximum purity. Physical characterization using western blot analysis showed that the extracted truncated PTH is intact and reacts with anti-PTH antibodies. In vitro analysis of PTH stimulated adenylyl cyclase activation in UMR 106 cells confirmed biological activity for purified protein. We believe this vector and production methodology represents a generally applicable tool for the generation of recombinant peptides.