TRYPTOPHAN-NORLEUCINE 1,5-DISUBSTITUTED TETRAZOLES AS CIS PEPTIDE-BOND MIMICS - INVESTIGATION OF THE BIOACTIVE CONFORMATION OF A POTENT AND SELECTIVE PEPTIDE FOR THE CHOLECYSTOKININ-B RECEPTOR

It has been suggested that the cis conformation about the Trp-N-MeNle amide bond is important in conferring high affinity and selectivity to CCK-B receptor ligands. Substitution of the cis amide bond mimic Trp psi(CN4)Nle into the peptide Gly-Trp-N-(Me)Nle-Asp-PheNH(2) causes it to lose activity, suggesting that other structural effects of N-(Me)Nle incorporation may be important for high affinity and selectivity for the CCK-B receptor.