Kawano Chiaki, Okada Kazushi, Honda Takeshi, Nose Takeru, Sakaguchi Kazuyasu, Costa Tommaso, Shimohigashi Yasuyuki
Laboratory of Structure-Function Biochemistry, Faculty and Graduate School of Sciences, Kyushu University, Fukuoka 812-8581, Japan.
J Pept Sci. 2002 Oct;8(10):561-9. doi: 10.1002/psc.415.
Ac-RYYRIK-NH2 is a peptide isolated from the peptide library as an antagonist that inhibits the biological activities of nociceptin, a hyperalgesic neuropeptide. In order to clarify the structural requirements of this peptide for binding to the nociceptin receptor ORL1, systematic structure-activity studies were carried out. The result of Ala-scanning indicated that the N-terminal tripeptide RYY(= Arg-Tyr-Tyr) is crucially important for binding to the ORL1 receptor. Residual truncations from the N- or C-terminus revealed the special importance of the N-terminal Arg residue. The removal of protecting groups indicated that the N-terminal acetyl group is essential, but the C-terminal amide group is insignificant. These results indicated the conspicuous importance of acetyl-Arg at position 1 of Ac-RYYRIK-NH2 as a key structure allowing binding to the receptor. To investigate the binding site of this peptide in the ORL1 receptor, we synthesized and assayed a series of analogues of the nociceptin dibasic repeat region, residues 8-13 of RKSARK. None of the derivatives were active. Ac-RYYRIK-NH2 was inactive for the mu opioid receptor to which nociceptin binds with considerable strength. All the results suggested that the mode of binding between Ac-RYYRIK-NH2 and the ORL1 receptor is different to that between the ORL1 receptor and nociceptin, and that it may consist of interaction with the receptor site to which nociceptin(1-7) or -(14-17) binds.
Ac-RYYRIK-NH2是从肽库中分离出的一种肽，作为拮抗剂可抑制伤害感受素（一种痛觉过敏神经肽）的生物活性。为了阐明该肽与伤害感受素受体ORL1结合的结构要求，开展了系统的构效关系研究。丙氨酸扫描结果表明，N端三肽RYY（=精氨酸-酪氨酸-酪氨酸）对于与ORL1受体结合至关重要。从N端或C端进行的残留截短显示出N端精氨酸残基的特殊重要性。去除保护基团表明N端乙酰基是必需的，但C端酰胺基并不重要。这些结果表明，Ac-RYYRIK-NH2第1位的乙酰化精氨酸作为允许与受体结合的关键结构具有显著重要性。为了研究该肽在ORL1受体中的结合位点，我们合成并检测了一系列伤害感受素双碱性重复区域（RKSARK的8-13位残基）的类似物。这些衍生物均无活性。Ac-RYYRIK-NH2对μ阿片受体无活性，而伤害感受素与该受体有相当强的结合力。所有结果表明，Ac-RYYRIK-NH2与ORL1受体之间的结合模式不同于ORL1受体与伤害感受素之间的结合模式，且可能由与伤害感受素（1-7）或-（14-17）结合的受体位点相互作用组成。
