Parray Zahoor Ahmad, Ahmad Faizan, Chaudhary Anis Ahmad, Rudayni Hassan Ahmad, Al-Zharani Mohammed, Hassan Md Imtaiyaz, Islam Asimul
Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, India.
Department of Chemistry, Indian Institute of Technology Delhi, New Delhi, India.
Front Mol Biosci. 2022 May 25;9:849683. doi: 10.3389/fmolb.2022.849683. eCollection 2022.
Even though there are a great number of possible conformational states, how a protein generated as a linear unfolded polypeptide efficiently folds into its physiologically active form remained a fascinating and unanswered enigma inside crowded conditions of cells. In this study, various spectroscopic techniques have been exploited to know and understand the effect and mechanism of action of two different sizes of polyethylene glycols, or PEGs (molecular mass ∼10 and ∼20 kilo Daltons, kDa), on cytochrome (cyt ). The outcomes showed that small size of the PEG leads to perturbation of the protein structure, and conversely, large size of the PEG has stabilizing effect on cyt . Moreover, binding measurements showed that small size of PEG interacts strongly soft interactions compared to the larger size of PEG, the latter being governed more by excluded volume effect or preferential exclusion from the protein. Overall, this finding suggests that conformations of protein may be influenced in cellular crowded conditions interactions which depend upon the size of molecule in the environment. This study proposes that both volume exclusion and soft (chemical) interactions governs the protein's conformation and functional activities. The cellular environment's internal architecture as evident from crowder size and shape in this study has a significant role.
尽管存在大量可能的构象状态，但在细胞拥挤的环境中，作为线性未折叠多肽产生的蛋白质如何有效地折叠成其生理活性形式，仍然是一个引人入胜且尚未解决的谜团。在这项研究中，人们利用了各种光谱技术来了解和理解两种不同大小的聚乙二醇（PEG，分子量约为10和20千道尔顿，kDa）对细胞色素c（cyt c）的作用效果和作用机制。结果表明，小尺寸的PEG会导致蛋白质结构的扰动，相反，大尺寸的PEG对细胞色素c具有稳定作用。此外，结合测量表明，与大尺寸的PEG相比，小尺寸的PEG通过软相互作用强烈相互作用，而大尺寸的PEG更多地受排除体积效应或从蛋白质中优先排除的影响。总体而言，这一发现表明，在细胞拥挤的环境中，蛋白质的构象可能会受到相互作用的影响，而这种相互作用取决于环境中分子的大小。这项研究表明，体积排除和软（化学）相互作用都决定了蛋白质的构象和功能活性。从本研究中拥挤剂的大小和形状可以明显看出，细胞环境的内部结构起着重要作用。
