Solid-phase synthesis and biologic activity of human parathyroid hormone (1-84).

We have chemically synthesized the full-length, 84 amino acid, human parathyroid hormone (hPTH) on a greater than 100 mg scale by the Merrifield solid-phase technique of stepwise peptide synthesis using a benzhydrylamine support. The peptide was purified by high-performance liquid chromatography and found to be greater than 96% pure. The authenticity or the sequence of the synthetic peptide was confirmed by repetitive Edman degradation. Furthermore, tryptic digestion of hPTH generated the predicted fragments. The synthetic full-length hormone was evaluated for biologic activity in assays of PTH receptor binding and stimulation of adenylate cyclase activity (using bovine renal cortical membranes and rat and human bone cells). Synthetic hPTH (1-84) was found to be highly potent in binding to PTH receptors (Kb = 1-25 nM) and stimulating adenylate cyclase (Km = 1-14 nM). The availability of significant quantities of synthetic full-length hPTH and future analogs will permit widespread use in multiple in vitro and in vivo assays to delineate their spectrum of biologic properties. Available supplies of the synthetic hormone will also enable evaluation of the effectiveness of PTH antagonists at inhibiting the action of native sequence hormone at its receptors.