Isolation of Circulating Immunoreactive Human Parathyroid Hormone: Comparison with a 1-34 N-Terminal Synthetic Fragment

Immunoreactive human parathyroid hormone (hPTH) was isolated from normal plasma by Sepharose bound antibodies raised against either the synthetic 1-34 fragment of hPTH (Niall sequence) or bovine PTH. The isolated material was compared with extracted hPTH, Quso extracts of adenoma cultures, hyperparathyroid plasma and the synthetic fragment using a radioimmunoassay homologous for this fragment. Complete cross reaction of all preparations studied was observed in this system, indicating that immunoreactive material separated from normal plasma by this method was identical with the synthetic peptide and implying that hPTH or its fragments present in normal and hyperparathyroid plasma. in tissue extracts or released in culture medium share common tertiary structures with the 1-34 peptide, synthetized according to the structure proposed by Niall et al.