Influence of Degradation on Binding Properties and Biological Activity of Endomorphin 1

Structure−Activity Study on the Phe Side Chain Arrangement of Endomorphins Using Conformationally Constrained Analogues

“…1 The C-terminal L-Phe in endomorphin-2 appears to generate the optimum µ receptor binding activity; however, D-Phe 4 and des-Phe 4 derivatives provided only a little lower affinity. 17,25,29 The negative impact of the Nterminal D-Tyr on µ affinity was found to be minimal. However, Phe 3 residue was quite essential, because its enantiomer reduced the µ affinity.…”

The Endomorphin System and Its Evolving Neurophysiological Role

“…Because of structural similarities to the parent compound, the degradation products might compete with endomorphins for the receptor binding site and could influence their biological activity. However, Szatmari et al (2001) demonstrated that the primary degradation products of endomorphin-1, Tyr-Pro-Trp-Phe-OH and Pro-Trp-Phe-OH, possess low -opioid receptor binding affinity, do not activate G-proteins and have no antinociceptive activity.…”

Characterization of opioid activities of endomorphin analogs with C-terminal amide to hydrazide conversion

“…Particularly, the rewarding effect of EMs can be separated from analgesia (Wilson et al, 2000), and they are less prone to induce respiratory depression and cardiovascular effects (Czapla et al, 2000), opening the possibility of pharmaceutical uses of EMs. They are also model peptides to determine the structure-activity relationship based on their typical characteristics of backbones and aromatic side chains (Szatmári et al, 2001;Okada et al, 2003).…”