Identification of new agonists of urotensin-II from a cyclic peptide library

The compound 1 ( c[GFWKYP]) was identified as an agonist of urotensin-II from our cyclic peptide library which consists of 360 peptides. Urotensin-II (UT-II) is thought to be involved in the regulation of cardiovascular homeostasis and pathology. A head-to-tail cyclic hexapeptide library based on UT-II sequence was designed, synthesized, and evaluated by the activity on the UT-II receptor (GPR-14). A new synthetic sequence, WK[Xaa] (Xaa: amino acid with aromatic side chain), was identified as a characteristic minimum fragment activating hUT-II receptor instead of the WK[Y] sequence. Compound 1 showed an agonistic activity with an EC 50 value of 6.94 nM. The conformational investigation suggested that 1 did not have typical secondary structure in the message sequence. Structural analyses may enable us to investigate the active conformation of UT-II and lead to the identification of new ligands for GPR-14.