Mechanism of thioflavin T binding to amyloid fibrils
Mechanism of thioflavin T binding to amyloid fibrils
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DOI：
10.1016/j.jsb.2005.06.006
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发表时间：
2005-09-01
影响因子：
3
通讯作者：
Singh, S
中科院分区：
文献类型：
--
作者：
Khurana, R;Coleman, C;Singh, S
硫代黄素T是一种苯并噻唑染料，在与淀粉样纤维结合时表现出增强的荧光，通常用于体外和体外诊断淀粉样纤维。在水溶液中，硫代黄素T被发现以胶束的形式存在，其浓度通常用于通过荧光分析来监测纤维(类似于10-20微米)。测定了硫代黄素T在不同浓度下的电导率变化，计算出临界胶束浓度为4.0+/-0.5微米。有趣的是，硫代黄素T的荧光激发和发射的变化也依赖于胶束的形成。用原子力显微镜直接观察到直径为3 nm的硫代黄素T胶束，并沿纤维长度观察到具有代表性的纤维的结合的硫代黄素T胶束。硫代黄素T浓度高于临界胶束浓度时，沿淀粉样蛋白纤维长度方向结合的胶束数目增加。原子力显微镜观察到硫代黄素T胶束在低pH时被破坏，当pH降到3以下时，硫代黄素T与淀粉样纤维结合时的荧光增强作用也减少了几倍。这表明硫代黄素T分子上的正电荷在其胶束形成中起作用，然后结合淀粉样纤维。我们的数据表明，硫代黄素T的胶束与淀粉样纤维结合，导致荧光发射增强。(C)2005 Elsevier Inc.保留所有权利。
Thioflavin T is a benzothiazole dye that exhibits enhanced fluorescence upon binding to amyloid fibrils and is commonly used to diagnose amyloid fibrils, both ex vivo and in vitro. In aqueous Solutions, thioflavin T was found to exist as micelles at concentrations commonly used to monitor fibrils by fluorescence assay (similar to 10-20 mu M). Specific conductivity changes were measured at varying concentration of thioflavin T and the critical micellar concentration was calculated to be 4.0 +/- 0.5 mu M. Interestingly, changes in the fluorescence excitation and emission of thioflavin T were also dependent on the micelle formation. The thioflavin T micelles of 3 nm diameter were directly visualized using atomic force microscopy, and bound thioflavin T micelles were observed along the fibril length for representative fibrils. Increasing concentration of thioflavin T above the critical micellar concentration shows increased numbers of micelles bound along the length of the amyloid fibrils. Thioflavin T micelles were disrupted at low pH as observed by atomic force microscopy and fluorescence enhancement upon binding of thioflavin T to amyloid fibrils also reduced by several-fold upon decreasing the pH to below 3. This suggests that positive charge on the thioflavin T molecule has a role in its micelle formation that then bind the amyloid fibrils. Our data suggests that the micelles of thioflavin T bind amyloid fibrils leading to enhancement of fluorescence emission. (C) 2005 Elsevier Inc. All rights reserved.