A high affinity, mu-opioid receptor-selective enkephalin analogue lacking an N-terminal tyrosine

A high affinity, mu-opioid receptor-selective enkephalin analogue lacking an N-terminal tyrosine (4-Carboxamido)phenylalanine is a surrogate for tyrosine in opioid receptor peptide ligands Ring substituted and other conformationally constrained tyrosine analogs of [cyclic] [D-Pen2,D-Pen5]enkephalin with .delta.-opioid receptor selectivity Stereospecific synthesis of (2 S )-2-methyl-3-(2′,6′-dimethyl-4′-hydroxyphenyl)-propionic acid (Mdp) and its incorporation into an opioid peptide Potent μ-Opioid Receptor Agonists from Cyclic Peptides Tyr-c[<scp>d</scp>-Lys-Xxx-Tyr-Gly]: Synthesis, Biological, and Structural Evaluation Enkephalin analogues with 2′,6′-dimethylphenylalanine replacing phenylalanine in position 4 Synthesis, opiate receptor affinity, and conformational parameters of [4-tryptophan]enkephalin analogs Further studies of tyrosine surrogates in opioid receptor peptide ligands Cyclic Enkephalin Analogues with Exceptional Potency and Selectivity for δ-Opioid Receptors Dermorphin tetrapeptide analogues with 2′,6′-dimethylphenylalanine (Dmp) substituted for aromatic amino acids have high μ opioid receptor binding and biological activities1