Gastrin-releasing peptide from the intestine of the elasmobranch fish, Scyliorhinus canicula (common dogfish)

The concentration of gastrin-releasing peptide in the intestine of the elasmobranchian fish, Scyliorhinus canicula, measured with an antiserum directed against the COOH-terminal region of porcine gastrin-releasing peptide, was higher than the concentrations measured in mammalian intestines. The immunoreactivity was resolved by gel permeation chromatography into two peaks with the approximate elution volumes of porcine gastrin-releasing peptide and bombesin/neuromedin C. The primary structure of the larger peptide was established as Ala Pro Val Glu Asn Gln Gly Ser Phe Pro Lys Met Phe Pro Arg Ser His (Trp) Ala Val Gly (His Leu Met · NH₂). Residues in parentheses are only tentatively assigned. Chromatographic evidence and the presence of the arginyl residue at position 15 in the peptide suggest that the smaller molecular form of gastrin-releasing peptide may be identical to mammalian neuromedin C. Amphibian bombesin was not identified in the dogfish gut.