A Tetrameric Enkephalin Analog for the Putative Multivalent Interaction with Opioid Receptors
作者:Michio Kondo、Hiroshi Kitajima、Teruo Yasunaga、Hiroaki Kodama、Tommaso Costa、Yasuyuki Shimohigashi
DOI:10.1246/bcsj.68.3161
日期:1995.11
Based on increased affinity and selectivity of dimeric enkephalin analogs for opioid receptors, divalent interactions have been demonstrated between opioid peptides and receptors. To explore the receptor multivalency suggested by fluorescent microscopic studies, a novel type of tetrameric enkephalin analog was designed and synthesized. The tetrameric enkephalin comprises four [d-Ala2, Leu5]enkephalin molecules coupled with the amino groups of the gem-diamino derivative of cystine, which was derived from cysteinamide by a Hofmann-type rearrangement, causing an amide-to-amine conversion. By the reduction of the gem-cystine disulfide bond in the tetramer, two dimeric analogs with a free or p-methoxybenzyl-protected mercapto group were also prepared. The receptor binding characteristics of these tetramer and dimers for the δ and μ receptors were analyzed in an NG108-15 cell and rat-brain membranes. The affinity of the tetrameric analog for the δ receptors was about equal to that of the dimers, but 2—4-fold lower for the μ receptors. The dimers were 5—8-fold δ-selective, and, thus, the tetramer exhibited a high selectivity for the δ receptors. A divalent interaction mechanism was considered between the tetrameric ligand and the δ opioid receptors.
基于二聚脑啡肽类似物对阿片受体的亲和力和选择性增加,已证明阿片肽和受体之间存在二价相互作用。为了探索荧光显微镜研究表明的受体多价性,设计并合成了一种新型四聚体脑啡肽类似物。四聚体脑啡肽由四个[d-Ala2, Leu5]脑啡肽分子组成,与胱氨酸的偕二氨基衍生物的氨基偶联,胱氨酸是通过霍夫曼型重排衍生自半胱酰胺,导致酰胺到胺的转化。通过还原四聚体中的偕胱氨酸二硫键,还制备了两种具有游离或对甲氧基苄基保护的巯基的二聚类似物。在 NG108-15 细胞和大鼠脑膜中分析了这些四聚体和二聚体对 δ 和 μ 受体的受体结合特征。四聚体类似物对δ受体的亲和力大约等于二聚体的亲和力,但对μ受体的亲和力低2-4倍。二聚体具有5-8倍δ选择性,因此四聚体对δ受体表现出高选择性。考虑了四聚体配体和δ阿片受体之间的二价相互作用机制。