Partial sequence and synthesis of urotensin I from Catastomus Commersoni.

The amino acid sequence (residues 4-34) of urotensin I, a 41 residue peptide from the urophysis of the Alberta white sucker Catastomus Commersoni, has been determined by a solid phase method. Based on the structure elucidated a peptide comprising residues 4-28 of urotensin I, Pro-Pro-Ile-Ser-Ile-Asp-Leu-Thr-Phe-His-Leu-Leu-Arg-Met-Ile-Glu-Met- Asn-Arg-Ile-Leu-Asn-Glu-Arg, was synthesized by a solid phase method. The synthetic peptide demonstrated no blood pressure lowering activity and did not block the hypotensive effect of native urotensin I in the rat. It appears that almost the entire sequence of urotensin I is required for binding to vascular receptors and that no "active region" is available in this regard.