Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran.
Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Int J Biol Macromol. 2018 May;111:870-879. doi: 10.1016/j.ijbiomac.2018.01.072. Epub 2018 Jan 17.
Protein fibrillation is a challenging issue in medicine, causing many diseases, and an impediment to pharmaceutics and protein industry. Many chemicals, especially polyphenol compounds and aromatic small molecules, have been widely used as an effective strategy to combat protein fibril formation. Hence, understanding mechanisms of fibrillation inhibition and contributing forces in this process are significant. In this study, the inhibitory effect of paclitaxel on lysozyme fibrillation was investigated with respect to thermal and colloidal stability. Fibrillation was monitored with ThT fluorescence, circular dichroism, and AFM; paclitaxel-lysozyme interaction with isothermal titration calorimetry and docking; thermal and colloidal stability with differential scanning calorimetry and zeta-pulse, respectively. Paclitaxel inhibited lysozyme fibrillation, and interacted with lysozyme through hydrogen bonds and van der Waals' interactions. The viability of PC12 cells retrieved as a result of fibrillation inhibition by paclitaxel. Hydrophobic forces dominantly shielded the aggregation-prone region of lysozyme and suppressed the effective interactions between lysozyme monomers. Although paclitaxel did not affect lysozyme's thermal stability, it increased lysozyme's colloidal stability by either increasing the surface charge density or charge distribution on lysozyme. In conclusion, our results suggest a model for paclitaxel's inhibitory role through two complementary steps driving to "off-pathway" oligomer formation and attenuation of fibril formation.
蛋白质纤维形成是医学领域的一个难题，它会引发多种疾病，并且对制药业和蛋白质工业也构成了阻碍。许多化学物质，尤其是多酚化合物和芳香族小分子，已被广泛用作对抗蛋白质纤维形成的有效策略。因此，了解纤维形成抑制的机制和该过程中的作用力至关重要。在这项研究中，研究了紫杉醇对溶菌酶纤维形成的抑制作用，主要是针对热稳定性和胶体稳定性。采用 ThT 荧光、圆二色性和原子力显微镜监测纤维形成；采用等温滴定微量热法和对接研究紫杉醇-溶菌酶相互作用；采用差示扫描量热法和 Zeta 脉冲分别研究热稳定性和胶体稳定性。紫杉醇抑制了溶菌酶纤维形成，并通过氢键和范德华相互作用与溶菌酶相互作用。紫杉醇抑制纤维形成使 PC12 细胞的活力得到恢复。疏水力主要屏蔽了溶菌酶易于聚集的区域，并抑制了溶菌酶单体之间的有效相互作用。虽然紫杉醇不影响溶菌酶的热稳定性，但它通过增加溶菌酶的表面电荷密度或表面电荷分布来提高溶菌酶的胶体稳定性。总之，我们的结果提出了一个紫杉醇抑制作用的模型，该模型通过两个互补步骤驱动“非典型”寡聚物形成和纤维形成的衰减。
