Peptide hormones identity

At the time of the discovery of Met-enkephalin, its sequence was observed to be identical to that of residues 61—65 contained in the C-fragment of the pituitary hormone p-Hpotropin [12584-99-5] (p-LPH) (see Hormones), first isolated in 1964 (11). In 1976, the isolation of a larger peptide fragment, P-endorphin [60617-12-1] that also displayed opiate-like activity was reported (12). This peptide s 31-amino-acid sequence comprised residues 61—91 of P-LPH. Subsequentiy, another potent opioid peptide, dynorphin [72957-38-17, was isolated from pituitary (13). The first five amino acids (qv) of this 17-amino-acid peptide are identical to the Leu-enkephalin sequence (see Table 1). 

Extensive drug screening is done at many athletic events, such as the Olympic Games. Usually, separate analyses, using different extraction procedures, are done for stimulants, narcotics, anabolic steroids, diuretics, and peptide hormones. In the analysis for stimulants, which are amines such as amphetamine and cocaine, a 5 rnL urine sample is first made basic with K.OH to ensure that the amines are present as the neutral molecules rather than as salts. The free amines are then extracted from the sample with diethyl ether. To save time and expense, the sample is first analyzed by gas chromatography only. If a peak appears with the retention time of one of the proscribed stimulants, then the sample is reanalyzed by GC/MS to confirm the identity of the suspected compound. 

Physicochemical Analysis Salmon calcitonin is a 32-amino-acid, nonglycosylated peptide hormone. It is structurally simple, possessing limited secondary structure and a single disulfide bond. The physicochemical characterization studies demonstrated that the primary and secondary structure of Fortical s recombinant salmon calcitonin (sc) was identical to that of Miacalcin s synthetic sc or naturally occurring sc. Further, the tertiary structures of the three were indistinguishable. 

The most valuable confirmation of this view to date is, without doubt, to be found in the known structures of homologous proteins and peptide hormones, that is compounds of identical biological function isolated from different species. As is well known, the primary structures of the homologous insulins, corticotropins, hypertensins, posterior pituitary hormones, and heme peptide sequences from cytochromes c are closely similar and differ only at certain definite sites in the peptide chains. These can, in particular, serve as a useful point of departure in a search for more general principles governing protein structure, and in the comparison of different proteins. 

Oxytocin is a hormone involved in controlling the onset of labour in women and the subsequent release of milk. It was the first peptide hormone to be synthesized, in 1953, and the synthetic version of the hormone, Syntooinon (identical, of course, with the natural version isolated... 

Peptide hormones are produced by the endocrine glands (pituitary, thyroid, pineal, adrenal, and pancreas) or by various organs such as the kidney, stomach, intestine, placenta, or liver (Table 3.4). Peptide hormones can have complex, convoluted structures with hundreds of amino acids. Figure 3.2 illustrates the chemical structure of human insulin and its three-dimensional shape. Insulin is made of two amino acid sequences. The A-Chain has 21-amino acids, and the B-Chain has 30-amino acids. The chains are linked together through the sulfur atoms of cysteine (Cys). Peptide hormones are generally different for every species, but they may have similarities [11]. Human insulin is identical to pig insulin, except that the last amino acid of the B-Chain for the pig is alanine (Ala) instead of threonine (Thr) (lUPAC and lUBMB) [9] and [11]. 

Hormones in humans, mammals, and other vertebrates are nearly identical in chanical structure and function. Although steroid hormones are completely identical among mammals, the structure of peptide hormones frequently differs among the animal species. This difference in structure can limit the ability of the peptide hormones from one species to another. The structure of the bovine... 

Llpotropin, lipotropic hormone, adlpokinetic hormone, LPH a polypeptide hormone from the hypophysis, that stimulates mobilization of lipids, especially fatty adds, from lipid depots. P-LPH contains 91 amino add residues, M, 9,894 (porcine). y-LPH contains 58 amino add residues, identical in sequence to residues 1-58 of P-LPH. Corticotropin, melanotropin, ACTH and LPH are all derived from a common precursor (see Peptides) they contain an identical hepta-peplide in their structures, and they are grouped together to form the ACTH family of peptide hormones. [J.Bogard etal. / Biol. Chem. 270 (1995) 23038-23043]... 

Oxytocin, a peptide which initiates uterine contractions during labour is identical in structure to ADH except at position 8 where a leucine residue replaces arginine. The close structural similarity but radically different biological functions, illustrate how specific some hormone receptors are in recognising only their own signal . 

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