Sulfonamide drugs binding to the colchicine site of tubulin: Thermodynamic analysis of the drug-tubulin interactions by isothermal titration calorimetry
Sulfonamide drugs binding to the colchicine site of tubulin: Thermodynamic analysis of the drug-tubulin interactions by isothermal titration calorimetry
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DOI：
10.1021/jm0494974
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发表时间：
2005-01-27
影响因子：
7.3
通讯作者：
Bhattacharyya, B
中科院分区：
文献类型：
--
作者：
Banerjee, M;Poddar, A;Bhattacharyya, B
几种磺胺类药物的发现为合成6(N-12-[(4-hydroxyphenyl)amino]-3-pyridinyl]-4-methoxybenzenesulfonamide：E7010和7(N-(3fluoro-4-methoxyphenyl)pentafluorobenzenesulfonamide，T138067铺平了道路，这两种药物都能抑制微管蛋白聚合，目前正在临床开发中。一系列含有吲哚支架的二芳基硫酰胺也被发现具有抗有丝分裂的特性，但到目前为止，它们与微管蛋白的相互作用模式仍未确定。在这项研究中：我们证明了这些磺胺类药物以可逆的方式与微管蛋白的秋水仙碱结合。他们猝灭了微管蛋白固有的色氨酸荧光，可能是由于药物诱导的蛋白质构象变化，但与增强相同酶活性的秋水仙素相比，他们无法调节微管蛋白的GTP酶活性。等温滴定量热法的进一步研究表明，5(N-(5-chloro-7-indolyl)-4-methoxybenzenesulfonamide)与微管蛋白的结合具有较大的热容变化正值(DeltaC(P)=+2 64，卡摩尔(-1)K-1)，这表明蛋白质发生了实质性的构象转变，并伴随着部分焓-熵补偿。从另一方面来说。2-氯代区域异构体2具有较大的负值DeltaC(P)(-589卡·摩尔(-1)·K~(-1))，并具有完全的热熵补偿。这种热力学分布被认为是由于药物-微管蛋白复合体中特定基团之间的范德华相互作用和氢键的显著贡献。这些结果表明，单一取代基氯在吲哚支架上位置的改变对药物-微管结合热力学有很大的影响。
The discovery of several sulfonamide drugs paved the way toward the synthesis of 6 (N-12-[(4-hydroxyphenyl)amino]-3-pyridinyl]-4-methoxybenzenesulfonamide: E7010) and 7 (N-(3fluoro-4-methoxyphenyl)pentafluorobenzenesulfonamide, T138067), both of which inhibit, tubulin polymerization and are under clinical development. A series of diarylsulforiamides containing an indole scaffold was also found to have antimitotic properties, but, their mode of interactions with tubulin has remained unidentified so far. In this study: we demonstrate that these sulfonamide drugs bind to the colchicine site of tubulin in a reversible manner. They quenched intrinsic tryptophan fluorescence of tubulin presumably due to drug-induced conformational changes in the protein, but were unable to modulate GTPase activity of tubulin in contrast to colchicine that enhances the same enzymatic activity. Further investigation using isothermal titration calorimetry (ITC) revealed that 5 (N-(5-chloro-7-indolyl)-4-methoxybenzenesulfonamide) afforded a large positive value of heat capacity change (DeltaC(p) = +264, cal mol(-1) K-1) on binding to tubulin, suggesting a substantial conformational transition in the protein along with partial enthalpy- entropy compensation. On the other hand. the 2-chloro regioisomer 2 gave a large negative value of DeltaC(p) (-589 cal mol(-1) K-1) along with complete enthalpyentropy compensation. This thermodynamic profile was thought to be attributable to a prominent contribution of van der Waals interaction and hydrogen bonding between Specific groups in the drug-tubulin complex. These results indicate that a mere alteration in the position of a single substituent chlorine on the indole scaffold has a great influence on the drug-tublin binding thermodynamics.