Biochemical and pharmacological characterization of three opioid-nociceptin hybrid peptide ligands reveals substantially differing modes of their actions

Abstract

In an attempt to design opioid-nociceptin hybrid peptides, three novel bivalent ligands, H-YGGFGGGRYYRIK-NH, H-YGGFRYYRIK-NH and Ac-RYYRIKGGGYGGFL-OH were synthesized and studied by biochemical, pharmacological, biophysical and molecular modelling tools. These chimeric molecules consist of YGGF sequence, a crucial motif in the N-terminus of natural opioid peptides, and Ac-RYYRIK-NH which was isolated from a combinatorial peptide library as an antagonist or partial agonist that inhibits the biological activity of the endogenously occurring heptadecapeptide nociceptin. Solution structures for the peptides were studied by analysing their circular dichroism spectra. Receptor binding affinities were measured by equilibrium competition experiments using four highly selective radioligands. G-protein activating properties of the multitarget peptides were estimated in [S]GTPγS binding tests. The three compounds were also measured in electrically stimulated mouse vas deferens (MVD) bioassay. H-YGGFGGGRYYRIK-NH (BA55), carrying N-terminal opioid and C-terminal nociceptin-like sequences interconnected with GGG tripeptide spacer displayed a tendency of having either unordered or β-sheet structures, was moderately potent in MVD and possessed a NOP/KOP receptor preference. A similar peptide without spacer H-YGGFRYYRIK-NH (BA62) exhibited the weakest effect in MVD, more α-helical periodicity was present in its structure and it exhibited the most efficacious agonist actions in the G-protein stimulation assays. The third hybrid peptide Ac-RYYRIKGGGYGGFL-OH (BA61) unexpectedly displayed opioid receptor affinities, because the opioid message motif is hidden within the C-terminus. The designed chimeric peptide ligands presented in this study accommodate well into a group of multitarget opioid compounds that include opioid-non-opioid peptide dimer analogues, dual non-peptide dimers and mixed peptide- non-peptide bifunctional ligands.

Anti-Oxidant and Tyrosinase Inhibitory In Vitro Activity of Amino Acids and Small Peptides: New Hints for the Multifaceted Treatment of Neurologic and Metabolic Disfunctions

“…As a prosecution of our ongoing research on bioactive peptides [16,17,18,19], we were interested at first in a comparative in vitro investigation on the anti-oxidant properties of sulfurated amino acids considered either as single units or incorporated in small peptides. Sulfur-containing compounds under study included L-cysteine (Cys) ( 1 ) with the related thiol-tripeptides, glutathione [H-Glu(Cys-Gly-OH)-OH, GSH] ( 2 ), and its synthetic gamma-oxa-analogue H-Glo(Cys-Gly-OH)-OH ( 3 ), and the amino acids, L-cystine ( 4 ), L-ergothioneine (EGT) ( 5 ), and taurine (Tau) ( 6 ) (Figure 1).…”

Synthesis, Biological Activity and Molecular Docking of Chimeric Peptides Targeting Opioid and NOP Receptors

“…Recently, Erdei et al [ 59 , 67 ] described three hybrid ligands, combining Ac-RYYRIK-NH 2 with N-terminal tetra- or pentapeptide sequences of DOP and KOP agonists, i.e., Leu-enkephalin and dynorphin. Both fragments were linked either directly or through a 3-Gly spacer.…”

Potential of Nociceptin/Orphanin FQ Peptide Analogs for Drug Development

“…Recently, Erdei et al [107] . described three hybrid ligands BA55, BA61, BA62 ( Figure 5), combining N‐terminal opioid tetra‐ or pentapeptide sequences (Tyr‐Gly‐Gly‐Phe or Tyr‐Gly‐Gly‐Phe‐Leu) crucial for activity of enkephalins and dynorphin, with the same NOP receptor recognizing synthetic peptide Ac‐RYYRIK‐NH 2 ( Figure 5).…”

“…administration but repeated daily injections led to the development of analgesic tolerance. [106] Recently, Erdei et al [107] described three hybrid ligands BA55, BA61, BA62 ( Figure 5), combining Nterminal opioid tetra-or pentapeptide sequences (Tyr-Gly-Gly-Phe or Tyr-Gly-Gly-Phe-Leu) crucial for activity of enkephalins and dynorphin, with the same NOP receptor recognizing synthetic peptide Ac-RYYRIK-NH 2 ( Figure 5). Two hybrids contained the Tyr-Gly-Gly-Phe message sequence.…”