Radioligand binding properties of VV-hemorphin 7, an atypical opioid peptide

J. Szikra, S. Benyhe, G. Orosz, Zs Darula, J. M. Piot, I. Fruitier, K. Monory, J. Hanoune, A. Borsodi

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Receptor binding properties of the hemoglobin-derived nonapeptide VV-hemorphin 7 (Val-Val-Tyr-Pro-Trp-Thr-Gln-Arg-Phe-OH) were studied using both the unlabelled form and tritium-labelled derivative of the peptide. In binding studies using selective opioid radioligands, VV-hemorphin 7 exhibited a rank order of potency of μ > κ ≫ δ. VV-hemorphin 7 was tritiated resulting in a compound with 1.03 TBq/mmol (27.8 Ci/mmol) specific radioactivity. The maximal number of binding sites was found to be 66.5 pmol/mg protein with an affinity of 82.1 nM in rat brain membranes. In competition studies, marked similarity was observed to the binding profile of the naturally occurring opioid heptapeptide Met-enkephalin-Arg-Phe (MERF) and its analogues to their naloxone-insensitive binding site. The common -Arg-Phe sequence at the carboxyl terminal end, which is similar to those of other endogenous peptides (-Arg-Phe-NH2 in neuropeptide FF and FMRF-NH2) brings attention to the C-terminal end of the molecule and points to the possible existence of a common nonopioid binding site in mammals.

Original languageEnglish
Pages (from-to)670-677
Number of pages8
JournalBiochemical and biophysical research communications
Issue number3
Publication statusPublished - Jan 1 2001



  • Naloxone-insensitive binding site
  • Radio-ligand binding
  • Tritiated peptide
  • VV-hemorphin 7

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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