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.