Pseudoproline-containing analogues of morphiceptin and endomorphin-2: Evidence for a Cis Tyr-Pro amide bond in the bioactive conformation
Analogues of the opioid peptides [D-Phe3]morphiceptin (H-Tyr-Pro-D-Phe-Pro-NH2) and endomorphin-2 (H-Tyr-Pro-Phe-Phe-NH2) containing the pseudoproline (ψPro) (4R)-thiazolidine-4-carboxylic acid (Cys[ψR1,R2pro])