Human Parathyroid Hormone: Amino-Acid Sequence of the Amino-Terminal Residues 1-34

Abstract

Human parathyroid hormone has been isolated in highly purified form from human parathyroid adenomas. The primary sequence of the amino-terminal 34 residues of the human hormone was obtained by automated degradation with a Beckman Sequencer. The phenylthiohydantoin amino acids were identified by gas chromatography and mass spectrometry. The first 34 residues of human parathyroid hormone differ from the bovine hormone by six residues, and from the porcine hormone by five residues. The amino-terminal residue is serine, similar to the porcine parathyroid hormone; bovine parathyroid hormone contains an amino-terminal alanine. Human parathyroid hormone contains two methionine residues, similar to the bovine species, whereas porcine parathyroid hormone contains a single methionine residue. Amino-acid residues in the first 34 that are unique to the human sequence include an asparagine at position 16, glutamine at position 22, lysine at position 28, and a leucine at position 30.During the last few years, a significant core of information has been obtained by several laboratories on the chemistry, biosynthesis, and secretion of parathyroid hormone (PTH). These studies have indicated that this hormone is initially synthesized as a prohormone, proparathyroid hormone (1-4). Proparathyroid hormone contains about 106 amino acids, and has an apparent molecular weight of 12,500 (4). The prohormone is rapidly converted into the storage or glandular form of the hormone, which consists of 84 amino acids and has a molecular weight of 9500. The complete amino-acid sequences of the 84 amino-acid parathyroid hormone from bovine (5, 6) and porcine (7) species have been reported. After appropriate physiological stimuli, the 9500 molecular weight form of the parathyroid hormone is secreted into the circulation (8). Shortly after entering the peripheral circulation, the glandular form of the hormone is cleaved into smaller fragments. Gel filtration of human hyperparathyroid serum by several investigators has revealed a major immunoreactive fragment(s), with a molecular weight of 5000-8000, and several minor components (8-10). Immunochemical heterogeneity of the circulating human parathyroid hormone, presumably due to the different molecular forms of PTH, was initially reported by Berson and Yalow (11), and has been confirmed by others (12, 13). The specific site(s) of cleavage in the 84-amino-acid polypeptide chain of the parathyroid hormone in the general circulation is unknown. A biologiAbbreviation: PTH, parathyroid hormone cally active pel)tide fragment of bovine 1PTH, prepared by dilute acid cleavage, has been relported (14, 15), a result indicating that the intact 84-amino-acid polyl)eptide is not needed for biological activity. This peptide has been identified as the amino-terminal peptide of the hormone, and is composed of the initial 30 residues of the sequence (15). Synthetic lel)tides of the first 34 residues of the bovine hormone (16) and the initial 30 residues of the porcine hormone (17) have been prepared and are bio...

Human Parathyroid Hormone IMMUNOLOGICAL CHARACTERIZATION OF ANTIBODIES AGAINST A GLANDULAR EXTRACT AND THE SYNTHETIC AMINO-TERMINAL FRAGMENTS 1-12 AND 1-34 AND THEIR USE IN THE DETERMINATION OF IMMUNOREACTIVE HORMONE IN HUMAN SERA

“…Its NH2-terminal amino acid sequence (residues 1-34) was determined by Brewer, Fairwell, Ronan, Sizemore, and Arnaud (20), and the biologically active (21,22) hPTH-(1-34) was synthesized by Andreatta et al (22). Subsequently, we gave a preliminary account of the immunochemical properties of the synthetic NH2-terminal PTH fragment (23).…”

“…They were quantitated on the basis of their capacity to bind [9I]-hPTH- (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12), [1I]hPTH- or ["lI]bovine PTH (bPTH- ). The quality of the antibodies was assessed by reference to inhibition of their interaction with labeled peptides by synthetic hPTH comprising 34 NH2-terminal amino acid residues or fragments thereof [hPTH- (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12), - , - (18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34), - (25)(26)(27)(28)(29)(30)(31)(32)…”

In vitro relative biological activities of (1–34) N‐terminal synthetic fragments of human parathyroid hormone in the human renal cortical adenylate cyclase assay

“…Two sequences differing in the amino acids at 3 positions have been reported for the )N-terminal fragment of human parathyroid hormone by Brewer et al [ 1,2] and subsequently by Niall et al [3,4] (fig.1). These two structures have been shown to be biologically active in both in vivo and in vitro assay systems [S-9] .…”

Immunoreactive Forms of Circulating Parathyroid Hormone in Primary and Ectopic Hyperparathyroidism

“…At the dilution used in these studies, GP 1M antiserum does not react with either synthetic bPTH (Beckman Instruments, Inc.) or human NH2-terminal PTH (10) and therefore is considered to be specific for the COOH-terminal region of PTH . In the present studies, values for iPTH were expressed in terms of highly purified human PTH (11).…”