Studies on peptides. CXXXIII. Synthesis and biological activity of galanin, a novel porcine intestinal polypeptide

A new porcine gastrointestinal 29-residue peptide, galanin, was synthesized in a satisfactory yield by assembling seven peptide fragments followed by deprotection with 1 M trifluoromethane-sulfonic acid-thioanisole in trifluoroacetic acid. Nin-Mesitylenesulfonyltryptophan was employed to suppress indole alkylation during Na-deprotection. β-Cycloheptylaspartate was employed to suppress base-catalyzed succinimide formation. The synthetic peptide exhibited a powerful contractile activity on rat ileum, but not on guinea pig ileum and caused sustained hyperglycemia in dogs.