12584-96-2 Usage
Description
PARATHYROID HORMONE (PTH) is a single-chain polypeptide hormone composed of 84 amino acid residues, with a molecular weight of 9,500. It is the first hormone isolated from the parathyroid gland and is known for its hypercalcemic action. PTH plays a crucial role in regulating blood calcium levels, bone metabolism, and is a drug target for hypoparathyroidism and osteoporosis. PTH is soluble in water and stable at pH 4.5, but it is relatively unstable in collected blood samples and hydrolyzes easily during storage.
Uses
1. Used in Pharmaceutical Industry:
PARATHYROID HORMONE is used as an antiosteoporotic for the treatment of osteoporosis. It helps in the regulation of bone metabolism and blood calcium levels, making it a potential therapeutic agent for bone and mineral diseases and disorders.
2. Used in Diagnostic Industry:
PARATHYROID HORMONE is used as a diagnostic aid for conditions such as pseudohypoparathyroidism and hypocalcemia. Its measurement in blood samples can help in the diagnosis and monitoring of these conditions.
3. Used in Clinical Trials:
PARATHYROID HORMONE has been used in clinical trials as a therapeutic agent for osteoporosis. The N-terminal fragments of PTH and PTHrP, comprising amino acids 1–34, have biological activities similar to those of the complete molecules, making them potential candidates for drug development.
4. Used in Research and Development:
PARATHYROID HORMONE and its analogs, such as PTH (1–14) and PTH (1–21), show high-affinity binding and efficient activation of the PTH1R. These analogs are being studied for their potential applications in the treatment of various bone-related conditions.
Brand Name:
Paroidin (Parke-Davis) is a brand name for PARATHYROID HORMONE.
Agonists and Antagonists:
The N-terminal fragments of PTH and PTHrP, comprising amino acids 1–34, have biological activities similar to those of the complete molecules. Some analogs, such as [Leu11, D-Trp12] PTHrP (7–34) and [Ile5, Trp23] PTHrP (5–36), bind with high affinity to PTH1R but are devoid of signaling activity. The PTH2R agonist, TIP39, binds efficiently to the PTH1R but does not activate it, and thus functions as a weak antagonist at this receptor.
Gene and mRNA
The human PTH gene is located on chromosome
11 (11p15.3-p15.1). The human PTH and chicken pth
genes comprise two introns that divide the gene into
three exons, encoding the 50
-untranslated region (UTR),
the signal peptide, the mature peptide, and the 30
-UTR. The pth gene structures of pufferfish are
similar to those of tetrapods, which include three exons
divided by two introns.
Synthesis and release
Extracellular calcium is the primary regulator of PTH
secretion from the parathyroid gland. In mammals and
birds, the circulating levels of PTH are greatly altered
by minute changes in the blood calcium concentration. PTH secretion is modulated by the action of the
calcium-sensing receptor (CaSR), which is located in
the parathyroid gland. Under hypercalcemic conditions,
Ca2+ binding to CaSR inhibits PTH secretion. Whereas,
under hypocalcemic conditions, the receptor is not occupied by extracellular Ca2+, resulting in PTH secretion. In
addition, 1,25(OH)2D3 acts directly on the parathyroid
gland and suppresses the transcription rate of the PTH
gene.
Receptors
The organization of the PTH1 receptor (PTH1R) gene
is highly homologous in three mammalian species,
namely the rat, human, and mouse. This gene extends
over 22 kb and contains at least 15 exons and 14 introns.
The human gene was mapped to chromosome 3p21.1-
p22. Both PTH and parathyroid hormone-related protein
(PTHrP) bind to the PTH1R. As both peptides signal
through the same receptor, it is also called the PTH/
PTHrP receptor. In contrast, the PTH receptor type 2
(PTH2R) is not activated by PTHrP but by PTH and a
tuberoinfundibular peptide of 39 amino acids (TIP39). TIP39 is known as a ligand of PTH2R, although the similarity of sequence between TIP39 and PTH is low. In addition to PTH1R and PTH2R, zebrafish
and other teleosts possess a third receptor, PTH3R, which may be derived by the duplication of
PTH1R. PTHRs share the same basic structure (seven transmembrane domains) with that of the class B G-protein
coupled receptor (GPCR) superfamily. A defining feature
of the class B receptors is the relatively long extracellular
N-terminal domain, which comprises approximately 150
amino acids and is important for ligand binding. The
presence of six cysteine residues that are strictly conserved within the N-terminal domain of all class
B GPCRs suggests that three disulfide linkages are present and are of critical importance. Kd in human kidney
plasma membrane, canine kidney plasma membrane,
and chick bone cell membrane is 1–5 nM.
Indications
PTH is secreted from the parathyroid glands in response
to a low plasma concentration of ionized (free) calcium.
PTH immediately causes the transfer of labile calcium
stores from bone into the bloodstream. PTH increases
rates of dietary calcium absorption by the intestine indirectly
via the vitamin D3 system activation of enterocyte
activity.Within the kidney, PTH directly stimulates calcium
reabsorption and a phosphate diuresis.
Biosynthesis
Plasma calcium concentration is the principal factor regulating
PTH synthesis and release. The increase in PTH
synthesis and secretion induced by hypocalcemia is believed
to be mediated through activation of parathyroid
gland adenylyl cyclase and a subsequent increase in intracellular
cyclic adenosine monophosphate (cAMP).
Formation of PTH begins with the synthesis of several
precursor molecules. PreproPTH is the initial peptide
that is synthesized within the parathyroid gland,
and it serves as a precursor to both proPTH and PTH.
PreproPTH is formed within the rough endoplasmic
reticulum, transported into the cisternal space, and then
cleaved to form proPTH. The proPTH polypeptide is
transported into the cisternal space, where another proteolytic
cleavage occurs, forming PTH.
Biological Functions
Parathyroid hormone (PTH) is biosynthesized as a 115-amino-acid preprohormone in the rough endoplasmic
reticulum of the parathyroid gland and is cleaved to the prohormone (84 amino acids) in the cisternal space of
the reticulum. The active hormone is finally produced (34 amino acids; molecular weight, 9,500 dalton) in the
Golgi complex and is stored in secretory granules in the parathyroid gland. This gland is exquisitely sensitive
to serum calcium concentrations and is able to monitor these levels via calcium-sensing receptors (CaSR).
These cell surface receptors help cells to react to micromolar changes in the concentration of ionized calcium
in the serum. Binding of calcium to these receptors facilitates activation of phospholipase C and, ultimately,
inhibition of PTH secretion. The relatively short-acting PTH is secreted from the parathyroid gland chief cells
in response to a hypocalcemic state and serves to oppose the hormonal effects of calcitonin.
Pharmaceutical Applications
PTH (parathyroid hormone), which are called calciotropic hormones. PTH controls
the serum plasma level of Ca2+ by regulating the re-absorption ofCa2+ in the nephron, stimulating the
uptake of Ca2+ from the gut and releasing Ca2+ from the bones which act as a reservoir.
Mechanism of action
Unlike calcitonin, the biological activity of PTH resides solely in residues 1 to 34 in the amino terminus. Parathyroid
hormone decreases renal excretion of calcium, indirectly stimulates intestinal absorption of
calcium, and in combination with active vitamin D, promotes bone resorption by a complex, unknown mechanism, thereby elevating serum calcium concentrations. In addition, the
secretion of PTH stimulates the biosynthesis and release of the third hormone associated with calcium
homeostasis, vitamin D. When serum calcium concentrations are high, the release of PTH is inhibited
Clinical Use
Treatment of chronic hypoparathyroidism
Clinical Use
diagnose a variety of calcium metabolic disorders, such
as hyperparathyroidism, hypoparathyroidism, hypercalcaemia of malignancy, and chronic renal failure.
The skeletal actions of PTH are dependent on the pattern of its administration.12 Intermittent exposure to PTH
leads to a net increase in bone formation, whereas its continuous administration produces bone loss. Thus, the
bone anabolic capability of PTH strictly depends upon
its administration producing a transient peak level in
plasma. PTH is used for osteoporosis therapy because of its
ability to increase osteoblastogenesis and osteoblast survival. Furthermore, PTH is involved in the proliferation
and differentiation of chondrocytes because mutations in
the PTH1R have been identified in Jansen-type metaphyseal chondrodysplasia and Blomstrand-type lethal
chondrodysplasia.
Drug interactions
Potentially hazardous interactions with other drugs
Bisphosphonates: reduction of calcium-sparing effect
with alendronate - avoid.
Metabolism
Parathyroid hormone is metabolised in the liver and to a
lesser degree in the kidney. Parathyroid hormone is not
excreted from the body in its intact form. Circulating
carboxy-terminal fragments are filtered by the kidney, but
are subsequently broken to even smaller fragments during
tubular reuptake.
Parathyroid hormone is efficiently removed from the blood
by a receptor-mediated process in the liver and is broken
down into smaller peptide fragments. The fragments derived
from the amino-terminus are further degraded within the
These carboxy-terminal fragments are thought to play a role
in the regulation of parathyroid hormone activity
Structure and conformation
PTH is a single-chain nonglycosylated peptide. In
humans, PTH is synthesized as a 115-aa precursor polypeptide. The signal peptide is cleaved, and the mature
peptide is packed in secretory vesicles and then secreted
as an 84-aa peptide . Chicken PTH consists of
88 aa with a striking similarity to the mammalian PTHs in
the N-terminus. In the zebrafish and pufferfish, two PTH genes and one PTH-like protein gene have
been discovered. In addition, the elephant shark has
PTH1 and PTH2, although questions are left unanswered about the classification of these hormones in the
PTH/PTHrP family. The mature PTH in mammals comprises an 84-aa peptide, the sequence of which varies in nonmammalian vertebrates. Among teleost fish, humans, and
chickens, the amino acid identity of mature PTHs is
around 20%–25% and the sequence similarity is close to
40%. However, high sequence conservation is observed
among the first 34N-terminal amino acid residues of all
PTHs.
Check Digit Verification of cas no
The CAS Registry Mumber 12584-96-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,2,5,8 and 4 respectively; the second part has 2 digits, 9 and 6 respectively.
Calculate Digit Verification of CAS Registry Number 12584-96:
(7*1)+(6*2)+(5*5)+(4*8)+(3*4)+(2*9)+(1*6)=112
112 % 10 = 2
So 12584-96-2 is a valid CAS Registry Number.