| Popis: |
The heptadecapeptide nociceptin was identified as the ligand for the ORL1 (opioid receptor-like 1) receptor, which shares 60% sequence homology with the k opioid receptor. In contrast to the opioid peptides, the aromatic amino acid in position 1 can be substituted by non-aromatic residues, whereas the one in the 4-position is crucial for receptor binding [1]. To establish the structural requirements for binding and activation, the latter position residue was substituted by a variety of aromatic amino acids using nociceptin(l-13)-NH2 (NC-13) as parent peptide. Additionally, a series of cyclic analogs was designed in order to stabilize helical structures, and probe their contribution to the bio-active conformation, since analysis of the CD spectra of NC-13 revealed the existence of secondary structures. |
