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.