Isolation, amino acid sequence, synthesis, and biological activity of some oligopeptides from porcine spinal cord.

Four oligopeptides, designated SCP-3, SCP-4, SCP-5, and SCP-6, have been isolated and purified to homogeneity from porcine spinal cord. The amino acid sequences have been determined as pyroGlu-Gly, pyroGlu-Gly-Gly, Met-Met-Gly, and Asp-Ala-Gly-Ala-Gly, respectively. All of these peptides have been synthesized by conventional liquid-phase or solid-phase methods. The synthetic and extracted peptides showed identical behavior in a reverse-phase high-performance liquid chromatography system. SCP-3 and SCP-4 exhibited some significant inhibitory activity on the electrical stimulation-induced contractions of longitudinal muscle strip of guinea pig ileum, and SCP-5 showed some stimulating effect on the same preparation. The physiological significance of these purified peptides is being investigated.