家兔前叶皮质苯二氮受体的动力学与光亲和标记

采用放射配基结合分析法及光亲和标记技术研究家兔脑前叶皮质苯二氮受体的动力学特征及其分子基础。~3H]FNP与突触体膜P_2饱和结合的Hill系数为0.74,Scatchard分析为双曲线型。低温(0℃)条件下的动力学显示表观不均一性,但提高温度至25℃时,结合与解离过程均符合一位点反应模型。P_2膜制备与~8H]FNP光亲和标记后进行SDS-聚丙烯酰胺凝胶电泳仅见一条放射性区带,其表观分子量为56000±1600道尔顿。实验结果提示家兔前叶皮质中苯二氮受体可能以二种不同亲和力的构象存在。

Kinetics and photoaffinity labeling of benzodiazepine receptor in frontal cortex of rabbit brain

The kinetic and molecular characteristics of benzodia-zepine receptor in the frontal cortex of rabbit brain were studied with 3H]flunitrazepam binding and photoaffinity labeling. The crude syn-aptosomal membranes (P2) were prepared by standard methods. The analysis of saturation binding showed apparent heterogeneity with Hill coefficient of 0.74 and non-linear Scatchard plot. Computer analysis revealed KDI of 0.276 nM and Bmax1 of 0.33 pmol/mg protein and KD2 of 5.960 nM and Bmax2 of 3.70 pmol/mg protein. In the experiments of kinetics, the biphasic association and dissociation also were observed at an assay temperature of 0℃, After rising the temperature to 25℃, however, these two kinetic procedures all changed into the linearones, being simple bimolecular reaction. The photoaffinity labeling was induced by 2537A ultroviolet. One radioactive zone can be found after SDS-polyacrylamide gel electropho-resis and liquid scintillation. The apparent molecular weight of 56 000 ±1600 dolton was reported. These results suggested that benzodiazepine receptor in frontal cortex of rabbit brain may exist in multiple configurations which have two different affinities for benzodiazepines and can transform each other under some conditions.