Isolation, primary structure, and synthesis of human hypothalamic somatocrinin: growth hormone-releasing factor

The hypophysiotropic peptide, growth hormone-releasing factor (GRF), was isolated from human hypothalamic-hypophysial tissues by means of acid extraction, immunoaffinity chromatography, gel filtration, and two steps of reverse-phase high-performance liquid chromatography. Amino acid sequence determination using a gas-phase sequencer and reverse-phase liquid chromatography of the native peptide and its synthetic replicates showed its primary structure to be as follows: H-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-Ser -Asn-Gln-Glu-Arg-Gly-Ala-Arg-Ala-Arg-Leu-NH2, which is identical to that of the GRF recently isolated and characterized from a human pancreatic tumor that had caused acromegaly. Human hypothalamic GRF shows major homologies (93%, 89%, and 86%, respectively) when its primary structure is compared to that of the hypothalamic GRF from the porcine, bovine, caprine, and ovine species.