Gastrointestinal peptide hormone analogues

All derivatives of the C-terminal tetrapeptide fragment of gastrins with 17 amino acids elicit every physiological effect of the gastrin. This recognation led to detailed studies on the structure-activity relationships. In the case of cholecystokinin-pancreozymin, a substance consisting of 33 amino acids, the smallest sequence which possesses biological activity is the C-terminal octapeptide fragment. Synthesis of analogous derivatives of this fragment allowed the determination of the structural elements necessary to evoke the biological action.