Synthesis of peptides by the solid-phase method. V. Substance P and analogs

We have synthesized a series of 12 analogs of the undecapeptide substance P in order to perform a structure-activity study of this peptide. In the present work, each residue was substituted by L-alanine, and the C-terminal amide was replaced by the free carboxyl in order to pinpoint biologically important side chains and functional groups. The synthesis of the analogs was carried out by the automatic solid-phase method. Couplings were performed by the symmetrical anhydride procedure. After cleavage with liquid HF, the peptides were purified by gel filtration and ion-exchange chromatography. Their purity was assessed by thin-layer chromatography, paper electrophoresis, amino acid and elemental analyses, and high pressure liquid chromatography. They were tested for biological activity in vitro on the ileum of the guinea pig, the mesenteric vein of the rabbit, and the vas deferens of the rat, and in vivo by measuring their effect on the blood pressure of the rat.