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Mixed Macromolecular Crowding: A Protein and Solvent Perspective
ACS Omega ( IF 3.7 ) Pub Date : 2018-04-19 00:00:00 , DOI: 10.1021/acsomega.7b01864
Saikat Biswas 1 , Jayanta Kundu 1 , Sanjib K. Mukherjee 1 , Pramit Kumar Chowdhury 1
Affiliation  

In the living cell, biomolecules perform their respective functions in the presence of not only one type of macromolecules but rather in the presence of various macromolecules with different shapes and sizes. In this study, we have investigated the effects of five single macromolecular crowding agents, Dextran 6, Dextran 40, Dextran 70, Ficoll 70, and PEG 8000 and their binary mixtures on the modulation in the domain separation of human serum albumin using a Förster resonance energy transfer-based approach and the translational mobility of a small fluorescent probe fluorescein isothiocyanate (FITC) using fluorescence correlation spectroscopy (FCS). Our observations suggest that mixed crowding induces greater cooperativity in the domain movement as compared to the components of the mixtures. Thermodynamic analyses of the same provide evidence of crossovers from enthalpy-based interactions to effects dominated by hard-sphere potential. When compared with those obtained for individual crowders, both domain movements and FITC diffusion studies show significant deviations from ideality, with an ideal solution being considered to be that arising from the sum of the contributions of those obtained in the presence of individual crowding agents. Considering the fact that domain movements are local (on the order of a few angstroms) in nature while translational movements span much larger lengthscales, our results imply that the observed deviation from simple additivity exists at several possible levels or lengthscales in such mixtures. Moreover, the nature and the type of deviation not only depend on the identities of the components of the crowder mixtures but are also influenced by the particular face of the serum protein (either the domain I–II or the domain II–III face) that the crowders interact with, thus providing further insights into the possible existence of microheterogeneities in such solutions.

中文翻译:

大分子混合拥挤:蛋白质和溶剂的观点

在活细胞中,生物分子不仅在一种类型的大分子存在下,而且在具有不同形状和大小的各种大分子存在下执行其各自的功能。在这项研究中,我们研究了五种单一的大分子拥挤剂,Dextran 6,Dextran 40,Dextran 70,Ficoll 70和PEG 8000及其二元混合物对通过Förster共振作用对人血清白蛋白结构域分离的调节作用。基于能量转移的方法和使用荧光相关光谱(FCS)的小型荧光探针异硫氰酸荧光素(FITC)的平移迁移率。我们的观察结果表明,与混合成分相比,混合拥挤在域运动中诱导了更大的协作性。对它们的热力学分析提供了从基于焓的相互作用到硬球势主导的效应交叉的证据。当与针对单个拥挤者获得的那些相比较时,域运动和FITC扩散研究均显示出与理想性的显着偏差,其中一个理想的解决方案被认为是存在于单个拥挤剂中的那些人的贡献之和所产生的解决方案。考虑到域运动本质上是局部的(几埃量级),而平移运动的长度范围要大得多,我们的结果表明,在这种混合物中,观察到的与简单可加性的偏差存在于几种可能的水平或长度范围内。而且,
更新日期:2018-04-19
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