Opioid peptides. Synthesis and binding assays of desamino-Tyr1 dermorphin analogues. XII.

Eight new dermorphin peptides, X-C6H4-CH2CH2CO-D-Ala-Phe-(L or D)-Yaa-NH2 [X = H, OH; Y = lysine, homoarginine (Har)], were prepared and tested by binding assays. They show negligible affinity for mu-, delta- and K-receptor sites. These findings indicate that the N-terminal ammonium group can not be replaced by the ammonium or guanidinium function located at the side-chain in Lys or Har derivatives.