High Yield Expression of Human Recombinant PTH (1–34)

Human parathyroid hormone (hPTH), synthesized in the parathyroid gland as a linear peptide, is one of the key regulatory molecules in calcium homeostasis and bone resorption. The N terminus region of hPTH (1–34) is a functionally important part of the molecule that is sufficient and necessary for potently executing most of the hormonal actions. Therefore, hPTH (1–34) is considered to be an attractive therapeutic agent in the treatment of osteoporosis. Here, we describe a high yield expression and purification method for the production of hPTH (1–34) from Escherichia coli. The hPTH (1–34) was expressed as a fusion protein in soluble form, and found to be more than 25% of total proteins. The fusion protein was first purified by GST affinity chromatography and, after cleavage of GST with Factor Xa, the peptide (hPTH 1–34) was further purified by reversed phase Source-30™ chromatography. This double purification strategy produced 30mg/l of hPTH (1–34) with purity = 98%. The identity of the purified peptide was confirmed by mass spectrometry and N-terminal sequencing analysis. The biological activity of the peptide was confirmed in the rat osteogenic cell line UMR-106 by measuring cAMP levels, which were identical to hPTH standards, indicating that purified rhPTH (1–34) has full biological activity.