Binding of synthetic fragments of β-endorphin to nonopioid β-endorphin receptor.

Autor: Navolotskaya, Elena V., Kovalitskaya, Yulia A., Zolotarev, Yury A., Sadovnikov, Vladimir B.
Zdroj: Journal of Peptide Science; Oct2008, Vol. 14 Issue 10, p1121-1128, 8p
Abstrakt: Selective agonist of nonopioid β-endorphin receptor decapeptide immunorphin (SLTCLVKGFY) was labeled with tritium (the specific activity of 24 Ci/mmol). [3H]Immunorphin was found to bind to nonopioid β-endorphin receptor of mouse peritoneal macrophages ( Kd = 2.0 ± 0.1 n M). The [3H]immunorphin specific binding with macrophages was inhibited by unlabeled β-endorphin ( Ki = 2.9 ± 0.2 n M) and was not inhibited by unlabeled naloxone, α-endorphin, γ-endorphin and [Met5]enkephalin ( Ki > 10 µ M). Thirty fragments of β-endorphin have been synthesized and their ability to inhibit the [3H]immunorphin specific binding to macrophages was studied. Unlabeled fragment 12-19 (TPLVTLFK, the author's name of the peptide octarphin) was found to be the shortest peptide possessing practically the same inhibitory activity as β-endorphin ( Ki = 3.1 ± 0.3 n M). The peptide octarphin was labeled with tritium (the specific activity of 28 Ci/mmol). [3H]Octarphin was found to bind to macrophages with high affinity ( Kd = 2.3 ± 0.2 n M). The specific binding of [3H]octarphin was inhibited by unlabeled immunorphin and β-endorphin ( Ki = 2.4 ± 0.2 and 2.7 ± 0.2 n M, respectively). Copyright © 2008 European Peptide Society and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]
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