Spetea M, Monory K, Tömböly C, Tóth G, Tzavara E, Benyhe S, Hanoune J, Borsodi A
Biological Research Center, Hungarian Academy of Sciences, Szeged, H-6701, Hungary.
Biochem Biophys Res Commun. 1998 Sep 29;250(3):720-5. doi: 10.1006/bbrc.1998.9395.
The recently discovered endogenous mu receptor selective endomorphin 2 was prepared in tritiated form by a catalytic dehalogenation method resulting in a specific radioactivity of 1.98 TBq/mmol (53.4 Ci/mmol), and used for in vitro labelling of rat brain membranes. The binding was saturable, stereospecific and of high affinity (Kd: 0.97 and 1.12 nM based on kinetic and equilibrium binding studies, respectively). The maximal number of binding sites (Bmax) was found to be 114.8 fmol/mg protein. [3H]Endomorphin 2 was displaced by mu-receptor selective specific peptides and heterocyclic compounds with high affinity, whereas kappa and delta receptor specific ligands were much less potent. The Ki values of endomorphin 1 and 2 in inhibiting [3H]naloxone binding increased by 15-fold in the presence of 100 mM NaCl which indicates the agonist property of these peptides. Endomorphins stimulated [35S]GTPgammaS binding and inhibited adenylyl cyclase activity which also provides evidence for the agonist character of endomorphins.
最近发现的内源性μ受体选择性脑啡肽2通过催化脱卤法制备成氚化形式，比活度为1.98 TBq/mmol（53.4 Ci/mmol），并用于大鼠脑膜的体外标记。该结合具有饱和性、立体特异性和高亲和力（根据动力学和平衡结合研究，Kd分别为0.97和1.12 nM）。发现结合位点的最大数量（Bmax）为114.8 fmol/mg蛋白质。[3H]脑啡肽2被μ受体选择性特异性肽和具有高亲和力的杂环化合物取代，而κ和δ受体特异性配体的效力则低得多。在100 mM NaCl存在下，脑啡肽1和2抑制[3H]纳洛酮结合的Ki值增加了15倍，这表明这些肽具有激动剂特性。脑啡肽刺激[35S]GTPγS结合并抑制腺苷酸环化酶活性，这也为脑啡肽的激动剂特性提供了证据。
