Isolation from Porcine‐Intestinal Wall of a Vasoactive Octacosapeptide Related to Secretin and to Glucagon

Abstract

A polypeptide composed of 28 amino acid residues has been isolated from porcine upper intestinal wall. In addition to exhibiting several biological activities which may be attributed to a relaxant effect on vascular and systemic smooth muscle it stimulates exocrine pancreatic secretion in a secretin‐like fashion, with an apparent efficiency, on a molar basis, of 5–10% of that of secretin and also gives rise to hyperglycaemia with about 30% of the efficiency of glucagon. Structurally it resembles secretin and glucagon in having a histidyl‐seryl sequence N‐terminally. Of the amino acid residues commonly occurring in mammalian proteins the residues of cysteine/cystine, glycine, proline and tryptophan are absent from it.