Mechanism of colchicine binding to tubulin. Tolerance of substituents in ring C' of biphenyl analogues.
Mechanism of colchicine binding to tubulin. Tolerance of substituents in ring C' of biphenyl analogues.
复制标题
秋水仙碱与微管蛋白结合的机制。
DOI：
10.1021/bi00229a027
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发表时间：
1991
期刊：
影响因子：
2.9
通讯作者：
Timasheff,SN
中科院分区：
文献类型：
--
作者：
Andreu,JM;Gorbunoff,MJ;Medrano,FJ;Rossi,M;Timasheff,SN
修订稿于 1990 年 11 月 29 日收到摘要：通过合成许多类似物并检查它们与微管蛋白的结合及其后果，探讨了联苯秋水仙碱类似物环 C（秋水仙碱中的 C 环）位置 4' 取代基结构变化的限制。发现结合需要在三维空间中4/-取代基中的氧位于距秋水仙碱环C氧的位置不远的位置。所有与微管蛋白秋水仙碱位点结合的类似物均诱导 GTP 酶活性并抑制微管组装，其中那些含有亚化学计量的羰基，其他则含有化学计量的。秋水仙碱类似物-微管蛋白复合物的异常聚合的诱导也发现了类似的关系，含甲氧基的化合物需要更高的温度来诱导聚合。对秋水仙碱及其各种类似物的结合热力学的协同分析表明与先前提出的两步结合途径完全一致，该途径涉及配体中两个不同的结合部分[Andreu, J. M., & Timasheff, S. N.(1982) Biochemistry 21, 534-543]，秋水仙碱、其des（环B）类似物（MTC）以及环A和C化合物各自的结合参数的比较推导出秋水仙碱和 MTC 结合的第一步的热力学参数 [Engelborghs, Y., & Fitzgerald, T. J.(1987) J. Biol.。化学。 262, 5204-5209]得出这样的结论：结合可以通过两种途径发生，产生相同的产物。在第一个途径中，环A首先结合；接下来是决定速率的热力学无关反应（蛋白质构象变化），最后是环 C 的快速结合。在第二条途径中，除了环的结合顺序相反之外，事件是相同的。由于环 B 的空间位阻，秋水仙碱只能遵循第二条途径。对于 MTC，两条动力学途径都是开放的，并且可以通过环 A 或环 C 的随机首次接触来启动结合。
Revised Manuscript Received November 29, 1990 abstract: The limitsof structural variation of the substituent in position4'of ring C of biphenyl colchicine analogues (ring C in colchicine) were probed by the synthesis of a number of analogues and theexamination of their binding to tubulin and its consequences. Binding was found to require the location in three-dimensional space of the oxygen in the 4/-substituent at a locus not far distant from those of the colchicine ring C oxygens. All those analogues that bindto the colchicine site of tubulin induced the GTPase activity and inhibited microtubule assembly, those containing a carbonyl group substoichiometrically and the others stoichiometrically. A similar relation was found for the induction of the abnormal polymerization of the colchicine analogue-tubulin complex, with methoxy-containing compounds requiring a higher temperature to induce the polymerization. A concerted analysis of the binding thermodynamics of colchicine and its various analogues has shown full consistency with the previously proposed two-step binding pathwaythat involves two nonidentical binding moieties in the ligand [Andreu, J. M., & Timasheff, S. N.(1982) Biochemistry 21, 534-543], Comparison of the binding parameters of colchicine, its des (ring B) analogue (MTC), and ring A and C compounds individually with the thermodynamic parameters deduced for the first steps of the bindings of colchicine and MTC [Engelborghs, Y., & Fitzgerald, T. J.(1987) J. Biol. Chem. 262, 5204-5209] have led to the conclusion that binding can occur by two pathways leading to the identical product. In the first pathway, ring A binds first; this is followed by a rate-determining thermodynamically indifferent reaction (protein conformation change), and finally a rapid binding of ring C. In the second pathway, the events are the same except that the order of binding of the rings is reversed. Colchicine, due to the steric hindrance of ring B, can follow only the second pathway. For MTC, both kinetic pathways are open and binding may be initiated by random first contact of either ring A or ring C.