Polypeptide hormones synthesis

Three hormones regulate turnover of calcium in the body (22). 1,25-Dihydroxycholecalciferol is a steroid derivative made by the combined action of the skin, Hver, and kidneys, or furnished by dietary factors with vitamin D activity. The apparent action of this compound is to promote the transcription of genes for proteins that faciUtate transport of calcium and phosphate ions through the plasma membrane. Parathormone (PTH) is a polypeptide hormone secreted by the parathyroid gland, in response to a fall in extracellular Ca(Il). It acts on bones and kidneys in concert with 1,25-dihydroxycholecalciferol to stimulate resorption of bone and reabsorption of calcium from the glomerular filtrate. Calcitonin, the third hormone, is a polypeptide secreted by the thyroid gland in response to a rise in blood Ca(Il) concentration. Its production leads to an increase in bone deposition, increased loss of calcium and phosphate in the urine, and inhibition of the synthesis of 1,25-dihydroxycholecalciferol. 

V. du Vigneaud (New York) biochemically important sulfur compounds, especially the first synthesis of a polypeptide hormone. 

Atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and C-type natriuretic peptide (CNP) are members of a family of so-called natriuretic peptides, synthesized predominantly in the cardiac atrium, ventricle, and vascular endothelial cells, respectively (G13, Y2). ANP is a 28-amino-acid polypeptide hormone released into the circulation in response to atrial stretch (L3). ANP acts (Fig. 8) on the kidney to increase sodium excretion and glomerular filtration rate (GFR), to antagonize renal vasoconstriction, and to inhibit renin secretion (Ml). In the cardiovascular system, ANP antagonizes vasoconstriction and shifts fluid from the intravascular to the interstitial compartment (G14). In the adrenal cortex, ANP is a powerful inhibitor of aldosterone synthesis (E6, N3). At the hypothalamic level, ANP inhibits vasopressin secretion (S3). It has been shown that some of the effects of ANP are mediated via a newly discovered hormone, called adreno-medullin, controlling fluid and electrolyte homeostasis (S8). The diuretic and blood pressure-lowering effect of ANP may be partially due to adrenomedullin (V5). 

Vincent Du Vigneaud United States sulfur compounds of biological importance, synthesis of polypeptide hormone... 

While these steroids directly regulate sexual function, their synthesis and release are, in turn, controlled by gonadotropins — polypeptide hormones produced by the pituitary gland. The biology and medical applications of the gonadotropins are outlined in Chapter 8. Sex hormones produced naturally may be classified into one of three groups ... 

Mechanism of Action A polypeptide hormone that stimulates cartilaginous growth areas of long bones, increases the number and size of skeletal muscle cells, influences the size of organs, and increases RBC mass by stimulating erythropoietin. Influences the metabolism of carbohydrates (decreases insulin sensitivity), fats (mobilizes fatty acids), minerals (retains phosphorus, sodium, potassium by promotion of cell growth), and proteins (increases protein synthesis). Therapeutic Effect Stimulates growth. 

Insulin is a polypeptide hormone that consists of two peptide chains bonded by two disulfide bonds. The two chains are designated A and B. The A chain consists of 21 amino acids with a third internal disulfide bond, and the chain contains the remaining 30 amino acids. All vertebrates produce insulin and the structure is similar in these species. For example, the insulin produced in humans and porcine species differs by only one amino acid, and humans and bovine insulin differ by three amino acids. Insulin plays a crucial role in several physiological processes. These include the regulation of sugar in the body, fatty acid synthesis, formation of triglycerides, and amino acid synthesis. 

Site of synthesis and secretion Enzyme that degrades insulin and its source Half-life of insulin Insulin is a polypeptide hormone produced by thep cells of the islets of Langerhans of the pancreas. Its synthesis involves two inactive precursors, preproinsulin and proinsulin, which are subsequently cleaved to form the active hormone. Insulin is stored in the cytosol in granules that are released by exocytosis Insulin is degraded by the enzyme insulinase produced primarily by the liver. Insulin has a plasma half-life of approximately six minutes. 

Site of synthesis The counterregulatory hormones Glucagon is a polypeptide hormone secreted by the a cells of the pancreatic islets. Glucagon, along with epinephrine, Cortisol, and growth hormone (the "counterregulatory hormones"), opposes many of the actions of insulin. 

Polypeptide Hormones Are Stored in Secretory Granules after Synthesis Thyroid Hormones and Epinephrine Are Amino Acid Derivatives... 

Control of hormone synthesis and secretion in the anterior pituitary. Neurosecretory neurons in the hypothalamus liberate polypeptides that either stimulate or inhibit hormone synthesis by specialized pituitary cells containing the appropriate receptors. For example, GnRH stimulates gonadotroph cells in the pituitary to synthesize and secrete LH and FSH. These pituitary hormones then impinge on target cells, typically stimulating them to make other low-molecular-weight hormones. The end products of these cascades feedback-inhibit hormone production at either or both hypothalamic and pituitary levels. 

In this review, we will outline synthetic methods that have been developed for the synthesis of polypeptide hormones and neurotransmitters, and in the process we also point out the key analytical procedures that have been used in the synthesis and purification of these important biological natural products. See Table 1 for an overview of this article and its contents. 

Thyroid-stimulating hormone (TSH)—A polypeptide hormone secreted by the anterior pituitary gland that stimulates iodine uptake and thyroid hormone synthesis. 

Growth hormone (somatotropin) is a polypeptide synthesized and secreted by somatotrophs in the anterior pituitary. Growth hormone synthesis and secretion is stimulated by the hypothalamic peptide growth hormone-... 

FSH Follicle-stimulating hormone a polypeptide hormone that contains a and P subunits that is synthesized in and released from the anterior pituitary in response to binding of GnRH. When binding to receptors on the plasma membrane of the granulose cells of the ovarian follicle, it stimulates the synthesis and secretion of estradiol. 

ACTH Adrenocorticotropin, adrenocorticotropic hormone a polypeptide hormone released from the anterior pituitary into the bloodstream in response to the binding of CRH. ACTH binds to receptors in the adrenal cortex, causing the synthesis and release of cortisol. 

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