Mizuno S, Ogawa N, Mori A
Neurochem Res. 1984 Dec;9(12):1729-35. doi: 10.1007/BF00968083.
Receptors for benzodiazepines (BZ) and beta-carboline-carboxylic acid ethyl ester (beta-CCE) has been solubilized with decanoly-N-methylglucamide (DMG), a new kind of nonionic detergent. The apparent dissociation constants of diazepam and beta-CCE for solubilized receptor were similar to those for synaptic membranes. Sucrose density gradient centrifugation of the solubilized receptor protein revealed that the binding profile of [3H]beta-CCE essentially parallels that of [3H]diazepam and that both sedimentation coefficients were 10.5S. Co2+ and Ni2+, which increase [3H]diazepam binding and decrease [3H]beta-CCE binding to synaptic membranes, remarkably increased the binding of both to the solubilized receptor. Mg2+ and Ca2+, which had no effect on membrane receptor binding, also enhanced [3H]diazepam and [3H]beta-CCE binding to the solubilized receptor. The increase in binding in the presence of these divalent cations was due to a change in the apparent number of binding sites, with no change in binding affinities. The relative lack of specificity in divalent cation effects on solubilized BZ receptor may be caused by separation or destruction of the cation recognition site or channel of the BZ receptor complex by solubilization of the synaptic membrane with DMG.
苯二氮䓬（BZ）和β-咔啉羧酸乙酯（β-CCE）的受体已用新型非离子去污剂癸酰-N-甲基葡糖酰胺（DMG）进行了增溶。地西泮和β-CCE对增溶受体的表观解离常数与对突触膜的解离常数相似。对增溶受体蛋白进行蔗糖密度梯度离心显示，[3H]β-CCE的结合图谱与[3H]地西泮的结合图谱基本平行，且两者的沉降系数均为10.5S。能增加[3H]地西泮结合并减少[3H]β-CCE与突触膜结合的Co2+和Ni2+，显著增加了两者与增溶受体的结合。对膜受体结合无影响的Mg2+和Ca2+，也增强了[3H]地西泮和[3H]β-CCE与增溶受体的结合。在这些二价阳离子存在下结合的增加是由于表观结合位点数的变化，而结合亲和力没有变化。二价阳离子对增溶BZ受体作用的相对缺乏特异性，可能是由于用DMG增溶突触膜导致BZ受体复合物的阳离子识别位点或通道分离或破坏所致。
