DRUG-PROTEIN INTERACTIONS - BINDING OF CHLORPROMAZINE TO CALMODULIN, CALMODULIN FRAGMENTS, AND RELATED CALCIUM-BINDING PROTEINS
DRUG-PROTEIN INTERACTIONS - BINDING OF CHLORPROMAZINE TO CALMODULIN, CALMODULIN FRAGMENTS, AND RELATED CALCIUM-BINDING PROTEINS
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DOI：
10.1021/bi00322a020
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发表时间：
1985-01-01
期刊：
影响因子：
2.9
通讯作者：
WATTERSON, DM
中科院分区：
文献类型：
--
作者：
MARSHAK, DR;LUKAS, TJ;WATTERSON, DM
在热力学平衡的条件下，通过使用凝胶过滤法测量吩噻嗪药物与钙调蛋白、钙调蛋白片段和结构释放的Ca结合蛋白的定量结合。植物和动物钙调蛋白、肌钙蛋白C、S100 α。S100.beta。以Ca依赖性方式结合氯丙嗪，具有不同的化学计量和对药物的亲和力。钙调素和氯丙嗪之间的相互作用似乎是一个复杂的，钙依赖的现象。牛脑钙调素结合。5摩尔药物/摩尔蛋白质，在17 μ M药物下具有表观半最大结合。钙调素的大片段结合氯丙嗪的能力有限。含有残基1-90的最大片段仅保留了完整蛋白的药物结合活性的5%。氯丙嗪抑制钙调素刺激环核苷酸磷酸二酯酶的再研究进一步表明，反应组分之间存在复杂的多重平衡，并表明反应组分的添加顺序改变了超过10倍范围的活性半数最大抑制所需的药物浓度。这些结果证实了以前的观察使用固定吩噻嗪，表明钙调节蛋白质的一个子类绑定吩噻嗪在钙依赖的方式，并证明吩噻嗪和钙调素之间的相互作用比以前假设的更复杂。特异性、高亲和力、Ca依赖性药物结合活性需要能够形成适当构象的钙调蛋白分子的延伸区域。
The quantitative binding of a phenothiazine drug to calmodulin, calmodulin fragments and structurally released Ca binding proteins was measured under conditions of thermodynamic equilibrium by using a gel filtration method. Plant and animal calmodulin, troponin C, S100.alpha. and S100.beta. bind chlorpromazine in a Ca-dependent manner with different stoichiometries and affinities for the drug. The interaction between calmodulin and chloropromazine appears to be a complex, Ca-dependent phenomenon. Bovine brain calmodulin bound .apprx. 5 mol of drug per mol of protein with apparent half-maximal binding at 17 .mu.M drug. Large fragments of calmodulin had limited ability to bind chlorpromazine. The largest fragment, containing residues 1-90, retained only 5% of the drug binding activity of the intact protein. A reinvestigation of the chlorpromazine inhibition of calmodulin stimulation of cyclic nucleotide phosphodiesterase further indicated a complex, multiple equilibrium among the reaction components and demonstrated that the order of addition of components of the reaction altered the drug concentration required for half-maximal inhibition of the activity over a 10-fold range. These results confirm previous observations using immobilized phenothiazines that indicated a subclass of Ca-modulated proteins bound phenothiazines in a Ca-dependent manner, and demonstrate that the interaction between phenothiazine and calmodulins more complex than previously assumed. Extended regions of the calmodulin molecule capable of forming the appropriate conformation are required for specific, high-affinity, Ca-dependent drug binding activity.