Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi, 110025, India.
Department of Pharmacognosy College of Pharmacy, King Saud University, Riyadh, Saudi Arabia.
Sci Rep. 2021 Mar 19;11(1):6475. doi: 10.1038/s41598-021-85792-4.
One of the significant proteins that have attracted research groups due to virtue of being a potent selective anticancer drug target and property of triggering apoptosis upon release in cytoplasm is cytochrome c (cyt c). The mechanical transformations due to the macromolecular crowding in membrane in the mammalian cell are proposed to be useful inductors of changes in volume. It is very interesting to know that mitochondrial function were observed to be improved by polyethylene glycol (PEG) interaction, which in turn inhibits the cyt c (a pro-apoptotic cell death factor). In this work, the effect of polyethylene glycol of molecular weight 4 kilo Dalton (PEG 4 kDa) was investigated to highlight the structural transformations (tertiary and secondary structure) in cyt c using a choice of spectroscopic techniques (including UV-Vis absorption, near-UV, far-UV and Soret circular dichroism and fluorescence spectroscopy), which shows noteworthy shifts in the secondary and tertiary structures at higher concentrations of PEG 4 kDa with small changes in the heme-globular interactions. The size distribution changes of native protein treated with various concentrations of the crowder were observed and analyzed by dynamic light scattering (DLS). The interaction studies of the crowder with the protein was observed and analyzed by FTIR, isothermal titration calorimetry, time resolved fluorescence and molecular docking. The investigations suggested that the structural changes in the protein occurred due to soft interactions of PEG 4 kDa, which usually destabilizes proteins. The experimental evidence in this study proposed that crowding could be another approach to mechanical super-competition and free of certain markers that could aid in the identification and control of various diseases. This study suggests that crowders at specific concentrations, which softly interact with proteins, can be exploited as remedy for various diseases.
细胞色素 c（cyt c）是一种重要的蛋白质，由于其作为一种有效的选择性抗癌药物靶点的特性以及在细胞质中释放时触发细胞凋亡的特性，吸引了众多研究小组的关注。据推测，由于哺乳动物细胞质膜中大分子拥挤引起的机械变形是体积变化的有用诱导剂。有趣的是，已经观察到聚乙二醇（PEG）相互作用可改善线粒体功能，从而抑制细胞色素 c（促凋亡细胞死亡因子）。在这项工作中，研究了分子量为 4 千道尔顿的聚乙二醇（PEG 4 kDa）的影响，以使用多种光谱技术（包括紫外可见吸收、近紫外、远紫外和 Soret 圆二色性和荧光光谱）来突出细胞色素 c 的结构变化（三级和二级结构），结果表明在较高浓度的 PEG 4 kDa 下，二级和三级结构发生了显著变化，而血红素-球蛋白相互作用只有微小变化。通过动态光散射（DLS）观察和分析了用不同浓度致孔剂处理的天然蛋白质的大小分布变化。通过傅里叶变换红外光谱（FTIR）、等温滴定量热法、时间分辨荧光和分子对接观察和分析了致孔剂与蛋白质的相互作用。研究表明，蛋白质的结构变化是由于 PEG 4 kDa 的软相互作用引起的，这通常会使蛋白质不稳定。这项研究的实验证据表明，拥挤可能是另一种机械超竞争的方法，而且没有某些标记物，可以帮助识别和控制各种疾病。这项研究表明，在特定浓度下与蛋白质软相互作用的致孔剂可以被用作各种疾病的治疗方法。
