David-Pfeuty T, Simon C, Pantaloni D
J Biol Chem. 1979 Nov 25;254(22):11696-702.
Microtubule inhibitors can be classified into two categories: 1) those which inhibit the polymerization-dependent GTPase activity of phosphocellulose-purified tubulin, but induce a significant polymerization-independent GTPase activity (e.g. colchicine, griseofulvine, daunorubicine); 2) those which inhibit the GTPase activity associated with tubulin polymerization and that induced by inhibitors of the first class (e.g. the vincaalkaloids and podophyllotoxin). The colchicine-stimulated GTPase activity of tubulin appears to be due to the tubulin.colchicine complex. This suggests that colchicine inhibits tubulin assembly by binding to a tubulin-tubulin interaction site required for the polymerization-dependent GTPase activity and induces by itself a tubulin conformational change that leads to polymerization-independent GTPase activity. Stoichiometry of inhibition by vinblastine of the colchicine-stimulated GTPase activity is 1:2. On the other hand, the inhibition by vinblastine of the tubulin self-assembly and of the polymerization-dependent GTPase activity is strongly substoichiometric at the beginning of the polymerization reaction, 1 vinblastine molecule inhibiting the ability of 10 tubulin dimers to polymerize and to hydrolyze the GTP. However, at the polymerization plateau, the inhibition effect by vinblastine appears to be lower, suggesting a selective action of vinblastine on the early stages of the polymerization reaction.
1）那些抑制磷酸纤维素纯化微管蛋白的聚合依赖性GTP酶活性，但诱导显著的非聚合依赖性GTP酶活性的物质（如秋水仙碱、灰黄霉素、柔红霉素）；2）那些抑制与微管蛋白聚合相关的GTP酶活性以及由第一类抑制剂诱导的GTP酶活性的物质（如长春花生物碱和鬼臼毒素）。微管蛋白的秋水仙碱刺激的GTP酶活性似乎归因于微管蛋白-秋水仙碱复合物。这表明秋水仙碱通过结合聚合依赖性GTP酶活性所需的微管蛋白-微管蛋白相互作用位点来抑制微管蛋白组装，并自身诱导微管蛋白构象变化，导致非聚合依赖性GTP酶活性。长春碱对秋水仙碱刺激的GTP酶活性的抑制化学计量比为1:2。另一方面，在聚合反应开始时，长春碱对微管蛋白自组装和聚合依赖性GTP酶活性的抑制强烈低于化学计量比，1个长春碱分子抑制10个微管蛋白二聚体聚合和水解GTP的能力。然而，在聚合平台期，长春碱的抑制作用似乎较低，表明长春碱对聚合反应早期阶段有选择性作用。
