Interaction of Synthetic Peptide Octarphin with Human Blood Lymphocytes

---

Yu. N. Nekrasova¹, Yu. A. Zolotarev², and E. V. Navolotskaya^1*

¹Branch of Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, pr. Nauki 6, 142290 Pushchino, Moscow Region, Russia; fax: (4967) 330-527; E-mail: navolotskaya@fibkh.serpukhov.su; elenanavolots@gmail.com

²Institute of Molecular Genetics, Russian Academy of Sciences, pl. Kurchatova 2, 123182 Moscow, Russia; fax: (495) 196-0221; E-mail: zolya@img.ras.ru

^* To whom correspondence should be addressed.

Received October 10, 2012; Revision received November 6, 2012

---

The synthetic peptide octarphin (TPLVTLFK, fragment 12-19 of β-endorphin), a selective agonist of nonopioid β-endorphin receptor, was prepared with specific activity 28 Ci/mmol. The binding of [³H]octarphin to T and B lymphocytes isolated from the blood of donors was studied. It was found that [³H]octarphin binds both to T and B cells with high affinity: K_d = 3.0 ± 0.2 and 3.2 ± 0.3 nM, respectively. The specific binding of [³H]octarphin to T and B lymphocytes was competitively inhibited by unlabeled β-endorphin (K_i = 1.9 ± 0.2 and 2.2 ± 0.3 nM, respectively) and was not inhibited by unlabeled naloxone, [Met⁵]enkephalin, [Leu⁵]enkephalin, α-endorphin, and γ-endorphin. Thus, T and B lymphocytes of human blood possess a nonopioid β-endorphin receptor whose binding is provided by the fragment 12-19 (the octarphin sequence).

---

KEY WORDS: peptide, receptors, naloxone, β-endorphin, lymphocytes

DOI: 10.1134/S0006297913030140

---