Isolation and structure of another hypothalamic peptide possessing MSH-release-inhibiting activity

A second peptide with the biological activity of an MSH-release-inhibiting factor (MIF) and with the amino acid composition His 1, Arg 1, Pro 1, Gly 1, Phe 1 was isolated from bovine hypothalami. This pentapeptide, when subjected to the combined Edman-dansyl degradation, yielded the sequence Pro-His-Phe-Arg-Gly-NH 2, which was confirmed by derivatisation and mass spectral fragmentation. A peptide of similar structure was then synthesized. The chromagraphic and electrophoretic mobilities, biological activities, and mass spectral fragmentation patterns of the synthetic and natural peptides were compared and found to be similar. These studies suggest the existence of a hypothalamic pentapeptide, H-Pro-His-Phe-Arg-Gly-NH 2, possessing MIF-activity

Isolation and structure of hypothalamic MSH release-inhibiting hormone

MSH-release inhibiting hormone (MRIH) activity in bovine hypothalamic extracts, concentrated over 11,000-fold by gel filtration on Sephadex, was further purified by thin-layer chromatography. Two MRIH-active peptides were isolated; one showed a high and the other much weaker MRIH activity. The amino acid sequence of the main MRIH-active peptide, as determined by Edman degradation combined with the dansyl method, was shown to be prolyl-leucyl-glycine amide. These findings were confirmed by mass spectra. Synthetic L-Pro-L-Leu-glycine amide and the natural main MRIH-active peptide showed similar biological activities, chromatographic and electrophoretic mobilities, and mass spectral fragmentation patterns. This work indicates that the structure of bovine MRIH is L-Pro-L-Leu-Gly. NH 2

Distribution, Half-Life, and Excretion of 14C- and 3H-Labeled L-Prolyl-L-Leucyl-GIycinamide in the Rat

H-Pro-Leu-Gly-NH2, a potentinhibitor of melanocyte stimulating hormone (MSH) release [MSH-release inhibiting factor (MIF)], was labeled with 14C-leucine or 3H-proline and injected i.v. into rats. H-Pro-14C-Leu-Gly-NH2 was found to have a half-life of approximately 9 min and to be distributed in a space greater than that of the plasma volume. Relatively little radioactivity and no intact H-Pro-Leu-Gly-NH2 could be found in the urine 1 h after administration. 3H- and 14C-labeled-H-Pro-Leu-Gly-NH2 accumulated in the pineal, pituitary, kidney, liver, and adrenals; the elevated tissue to plasma ratio in the pineal, along with the identification of unchanged H-Pro-Leu-Gly-NH2 there, suggests the possibility of a direct influence of the hypothalamus upon the pineal gland

Synthesis of the porcine LH- and FSH-releasing hormone by the solid-phase method

The decapeptide (pyro)Glu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH 2, corresponding to the amino acid sequence of the porcine LH- and FSH-releasing hormone ( LH-RH FSH-RH ) has been synthesized by the solid phase method. After repurification, the synthetic product showed the same physico-chemical and biological properties as natural porcine LH-RH FSH-RH

Structure of the porcine LH- and FSH-releasing hormone. I. The proposed amino acid sequence

The complete amino acid sequence of porcine LH- and FSH- releasing hormone has been provisionally determined by the use on a micro-scale of the combined Edman-dansyl procedure coupled with the selective tritiation method for C-terminal analysis. These procedures were used directly on the digestion products of LH-RH with chymotrypsin and thermolysin, without separation of the fragments. Additional data were provided by high resolution mass spectral fragmentation of LH-RH. On the basis of these results, we propose the following decapeptide sequence for LH-RH: (pyro)Glu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH 2

Delayed Disappearance of 14C-Labeled-Pro-Leu-Gly-NH2 from the Blood of Hypophysectomized Rats

The disappearance of radioactivity after the injection of 14C-labeled-Pro-Leu-Gly-NH2, an MSH release-inhibiting factor (MIF-I), was measured in rats which had been subjected to various procedures. Delayed disappearance of the radioactivity to a small but statistically highly significant extent was found in hypophysectomized rats compared to rats with an intact pituitary. Pinealectomy and adrenalectomy did not change the half-time disappearance. Dehydration, hypothalamic destruction, or administration of excess saline, MSH, and large amounts of unlabeled MIF-I were all used as control procedures. These failed to demonstrate the mechanism by which the prolonged disappearance occurred, but did raise other questions. The half-time disappearance of tritiated inulin was not significantly different in hypophysectomized or intact rats. The results indicate that the absence of the pituitary gland prolongs the half-time disappearance of radioactivity from the blood of rats injected with labeled MIF-I

The Amino Acid Sequence of a Peptide with Growth

SUMMARY The amino acid sequence of a decapeptide with growth hormone-releasing activity, isolated from porcine hypo- thalami has been determined. The Edman dansyl procedure was used on the intact peptide and on fragments isolated from tryptic and papain digests. The sequence found was confirmed by the results of digestion with aminopeptidase M, leucine aminopeptidase, and carboxypeptidase A and B. On the basis of these studies the sequence of the decapeptide was established to be Val-His-Leu-Ser-Ala-Glu-Glu-Lys-Glu- Ala. The hypothalamus controls the secretion of growth hormone from the anterior pituitary gland (1). This control is mediated by a hypothalamic substance designated growth hormone-releas- ing hormone (2). The presence of this hormone has been demon- strated in hypothalamic extracts of nine mammals including man as well as in some birds and amphibia (3,4). We have previously described the isolation from porcine hypothalamic extracts of a polypeptide with GH-RH1 activity which depleted the pituitary growth hormone content in rats and stimulated the release of growth hormone in vitro (5). Later we showed that this poly- peptide enhanced the synthesis of growth hormone in tissue cul- tures (6), induced the extrusion of growth hormone containing granules from pituitary somatotrophs (7)) and increased plasma growth hormone-like activity (8). This polypeptide appeared homogeneous by thin layer chromatography and electrophoresis (5, 9). No evidence was found for any biologically active trace component or cofactor, noncovalently bound to this peptide (9). * This work was supported in part bv United States Public Health Service Grant m-07467 toA.V.S.- 1 The abbreviations used are: GH-RH. growth hormone-re- leasing hormone; dansyl-, l-dimethylamin~naphthalened-sulf- onyl-; LH, luteinizing hormone; FSH, follicle stimulating hor- mone, MSH, melanocyte-stimulating hormone. This paper describes the determination of the amino acid se- quence of this decapeptide

Isolation and properties of the FSH and LH-releasing hormone

LH-releasing hormone (LH-RH) was obtained in apparently a homogeneous state from extracts of pig hypothalami. The LH-RH preparation isolated has FSH-releasing hormone (FSH-RH) activity, which appears to be intrinsic to LH-RH. The amino acid composition of LH-RH/FSH-RH as determined on acid hydrolysates is: His 1, Arg 1, Ser 1, Glu 1, Pro 1, Gly 2, Leu 1 and Tyr 1. The hormone isolated stimulates the release of FSH and LH in vivo and in vitro in doses of a few nanograms. This polypeptide appears to represent the hypothalamic hormone which controls the secretion of both LH and FSH from the pituitary