Isolation, structure and biologic activity of chicken intestinal neurotensin.

Using a radioimmunoassay towards bovine neurotensin(NT), chicken NT has been purified to homogeneity from extracts of intestine and its amino acid sequence determined to be: less than Glu-Leu-His-Val-Asn-Lys-Ala-Arg-Arg-Pro-Tyr-Ile-Leu-OH. The molecule is identical to the bovine peptide except for the 3 amino acid substitutions located in its NH2-terminal half and italicized above (His/Tyr: Val/Glu; Ala/Pro). The structure for chicken NT is consistent with earlier immunochemical studies which indicated a COOH-terminal homology with bovine NT [1]. The peptide isolated was shown to be near equipotent with bovine NT in its ability to induce hypotension, hyperglycemia, and cyanosis in the anesthesized rat, underscoring the importance of the COOH-terminal residues in NT for biological activity.