Department of Medical Physics and Biophysics, Medical Faculty, Medical University-Sofia, Zdrave Str. 2, 1431 Sofia, Bulgaria.
Scientific Research Center, "St. Kliment Ohridski" Sofia University, 8 Dragan Tsankov Blvd., 1164 Sofia, Bulgaria.
Int J Mol Sci. 2024 Jun 21;25(13):6834. doi: 10.3390/ijms25136834.
Montmorillonite (MM) crystal nanoplates acquire anticancer properties when coated with the mitochondrial protein cytochrome (cytC) due to the cancer cells' capability to phagocytize cytC-MM colloid particles. The introduced exogenous cytC initiates apoptosis: an irreversible cascade of biochemical reactions leading to cell death. In the present research, we investigate the organization of the cytC layer on the MM surface by employing physicochemical and computer methods-microelectrophoresis, static, and electric light scattering-to study cytC adsorption on the MM surface, and protein electrostatics and docking to calculate the local electric potential and Gibbs free energy of interacting protein globules. The found protein concentration dependence of the adsorbed cytC quantity is nonlinear, manifesting a positive cooperative effect that emerges when the adsorbed cytC globules occupy more than one-third of the MM surface. Computer analysis reveals that the cooperative effect is caused by the formation of protein associates in which the cytC globules are oriented with oppositely charged surfaces. The formation of dimers and trimers is accompanied by a strong reduction in the electrostatic component of the Gibbs free energy of protein association, while the van der Waals component plays a secondary role.
蒙脱土（MM）晶体纳米片在被线粒体蛋白细胞色素 c（cytC）覆盖后获得抗癌特性，这是因为癌细胞具有吞噬 cytC-MM 胶体颗粒的能力。引入的外源 cytC 引发细胞凋亡：一种不可逆的生化反应级联反应，导致细胞死亡。在本研究中，我们通过使用物理化学和计算机方法——微电泳、静态和电动光散射——研究 cytC 在 MM 表面上的吸附，以及蛋白质静电和对接来计算局部电动势和相互作用蛋白球的吉布斯自由能，来研究 cytC 在 MM 表面上的吸附。发现吸附的 cytC 量的蛋白浓度依赖性是非线性的，表现出正协同效应，当吸附的 cytC 球占据 MM 表面的三分之一以上时，就会出现这种协同效应。计算机分析表明，协同效应是由形成蛋白质缔合物引起的，其中 cytC 球以带有相反电荷的表面取向。二聚体和三聚体的形成伴随着蛋白缔合的静电成分的强烈减少，而范德华成分则起次要作用。
