Human growth hormone releasing factor and somatostatin from two pancreatic tumors: isolation and characterization

Characterization of three peptides derived from prosomatostatin [prosomatostatin-(1-63)-, -(65-76)- and -(79-92)-peptides] in a human pancreatic tumour

By using only reverse-phase h.p.l.c., three fragments of prosomatostatin were isolated from an extract of a human pancreatic neuroendocrine tumour that produced somatostatin, vasoactive intestinal polypeptide and gastrin-releasing peptide. The amino acid composition of the peptides indicated that they represented prosomatostatin-(1-63)-peptide, prosomatostain-(65-76)-peptide and prosomatostatin-(79-92)-peptide (somatostatin-14). The identity of prosomatostatin-(1-63)-peptide was confirmed by characterization of the products of digestion with Armillaria mellea (honey fungus) proteinase. Partial micro-sequencing of prosomatostatin-(1-63)-peptide showed that the Gly24-Ala25 bond of preprosomatostatin was the site of cleavage of the signal peptide. Thus human prosomatostatin is a protein of 92 amino acid residues that is proteolytically cleaved in a pancreatic tumour at the site of a dibasic-residue (arginine-lysine) processing site and at a single-monobasic-residue (arginine) processing site.

Synthetic human growth hormone releasing factor (h-GRF-I-44-NH2) dose response effect on growth hormone and prolactin secretion in healthy adult men

The dose-effect relationship of an i.v. bolus of synthetic h-GRF-44 on growth-hormone and prolactin secretion has been studied. Seven healthy adult volunteers received in a random order h-GRF-44 2.5, 5, 10, 20, 40 and 80 micrograms and a placebo. Plasma growth hormone (GH) was determined between 30 min before and 240 min after injection, the area under the curve (AUC) and the peak GH level being used to assess the response. For both parameters a dose-effect relationship was observed. Doses as low as 2.5 micrograms were capable of eliciting a rise in GH plasma levels in few patients. Above 40 micrograms the dose-effect curves tended to plateau, although the decrease in the slope of the dose-effect curve at the peak was more marked. Intersubject variability was large, so precise determination of the minimal effective dose as well as the lowest dose giving a maximal effect was not possible. The available evidence suggests that the i.v. dose of synthetic h-GRF-44 (SR 95228) which is likely to promote GH release into the blood stream in most healthy adults is within the range 40-100 micrograms. In these healthy adults unwanted effects were infrequent with these low doses. Unlike previous experience with higher doses of another synthetic h-GRF-44, prolactin secretion in this study was not affected.

Chromosomal assignment of human sequences encoding arginine vasopressin-neurophysin II and growth hormone releasing factor

Complementary DNA clones encoding bovine vasopressin and human pancreas growth hormone releasing factor have been used to map homologous sequences in the human genome. Assignment of both cloned sequences to human chromosome 20 was accomplished by hybridization of insert DNAs to a panel of human-rodent somatic cell hybrids. Both these probes have been used to examine the structure of their respective genes in DNA from various individuals. No restriction fragment variants for growth hormone releasing factor have yet been found. Analysis of populations for restriction fragment length polymorphisms associated with disease states involving arginine vasopressin is underway.

Rat hypothalamic growth hormone-releasing factor: isolation, sequence analysis and total synthesis

Growth hormone-releasing factor (GRF) was isolated from acid extracts of approximately 35,000 rat hypothalami by means of immunoaffinity chromatography, gel filtration and two steps of reverse-phase HPLC. Amino acid analysis, gas-liquid phases sequencing and peptide mapping established that rat GRF is a 43 amino acid peptide with the amino acid sequence His-Ala-Asp-Ala-Ile-Phe-Thr-Ser-Ser-Tyr-Arg-Arg-Ile-Leu-Gly- Gln-Leu-Tyr-Ala-Arg-Lys-Leu-Leu-His-Glu-Ile-Met-Asn-Arg-Gln-Gln-Gly- Glu-Arg-Asn-Gln-Glu-Gln-Arg-Ser-Arg-Phe-Asn-OH, confirming the primary structure reported earlier (Spiess et al Nature 303, 532 (1983).

Growth hormone-releasing factor from ovine and caprine hypothalamus: isolation, sequence analysis and total synthesis

Peptides with high intrinsic growth hormone releasing activity (growth hormone-releasing factor, GRF) were isolated from 2100 ovine and 2600 caprine (goat) hypothalami by means of acid extraction, immunoaffinity chromatography, gel filtration and reverse phase HPLC. Structural characterization of the 44 amino acid ovine peptide by gas-liquid phase sequencing and peptide mapping established its primary structure as Tyr-Ala-Asp-Ala-Ile-Phe-Thr-Asn-Ser -Tyr-Arg-Lys-Ile-Leu-Gly-Gln-Leu-Ser-Ala-Arg-Lys-Leu-Leu-Gln-Asp-Ile-Met -Asn -Arg-Gln-Gln-GLy-Glu-Arg-Asn-Gln-Glu-Gln-Gly-Ala-Lys-Val-Arg-Leu-NH2. Caprine GRF was found to possess the same sequence except for the replacement of the isoleucine residue in position 13 with valine and thus is identical to bovine GRF.

Fragments of prosomatostatin isolated from a human pancreatic tumour

Six peptides from an extract of a human pancreatic tumour were purified to homogeneity by HPLC. Amino acid composition and chemical properties indicated probable structures the same as somatostatin-14, somatostatin-28 (1-12), [Met(O)8]somatostatin-28 (1-12), [Met(O)8]somatostatin-28 (1-10), somatostatin-25 (1-9) and [Met(O)5]somatostatin-25 (1-9). The structure of somatostatin-14 was confirmed by sequence analysis. The isolation of these peptides provides insight into the processing of prosomatostatin in the tumour cells.

Isolation and characterization of the bovine hypothalamic growth hormone releasing factor

A 44 amino acid peptide with high intrinsic growth hormone releasing activity was isolated from 500 bovine hypothalami by means of acid extraction, immunoaffinity chromatography, gel filtration, and two steps of reverse phase HPLC. The growth hormone releasing factor was structurally characterized by gas phase sequence analysis. Reverse phase liquid chromatography of the native peptide and synthetic replicates showed that the molecule possesses an amide rather than a free acid at its carboxyl terminus. The structure of the peptide was established as: Tyr Ala-Asp-Ala-Ile-Phe-Thr-Asn-Ser-Tyr-Arg-Lys-Val-Leu-Gly-Gln-Leu-Ser-Ala -Arg-Lys-Leu-Leu-Gln-Asp-Ile-Met-Asn-Arg-Gln-Gln-Gly-Glu-Arg-Asn-Gln -Gly-Ala-Lys-Val-Arg-Leu-NH2 using approximately 2 nmol of material.

Isolation and characterization of the porcine hypothalamic growth hormone releasing factor

A 44 amino acid peptide with high intrinsic growth hormone releasing activity was isolated from 2500 porcine hypothalami by means of acid extraction, immunoaffinity chromatography, gel filtration, and 2 steps of reverse phase HPLC. The growth hormone releasing factor was structurally characterized by gas phase sequence analyses of the intact peptide and its carboxyl terminal cyanogen bromide digestion fragment. Reverse phase liquid chromatography of the native peptide and synthetic replicates showed that the molecule possesses an amide rather than a free acid at its carboxyl terminus. The structure of the peptide was established as: Tyr-Ala-Asp-Ala-Ile-Phe-Thr-Asn-Ser-Tyr-Arg-Lys-Val-Leu-Gly-Gln-Leu-Ser-Ala-Arg-Lys-Leu-Leu-Gln-Asp-Ile-Met-Ser-Arg-Gln-Gln-Gly-Glu-Arg-Asn-Gln-Glu-Gln-Gly-Ala-Arg-Val-Arg-Leu-NH2 using approximately 6 nmol of material.