A Bulk Water-Dependent Desolvation Energy Model for Analyzing the Effects of Secondary Solutes on Biological Equilibria
A Bulk Water-Dependent Desolvation Energy Model for Analyzing the Effects of Secondary Solutes on Biological Equilibria
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DOI：
10.1021/bi1017717
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发表时间：
2011-03-29
期刊：
影响因子：
2.9
通讯作者：
Eggers, Daryl K.
中科院分区：
文献类型：
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作者：
Eggers, Daryl K.
提出了一种新的现象学模型来解释溶质对生物平衡的影响。该模型将平衡的变化归因于反应物质去溶剂化能的差异，而去溶剂化能的差异反过来又反映了添加次级溶质时大量水的自由能的变化。去溶剂化方法与其他溶质模型的显着不同，是将大量水的自由能视为变量，并且不将观察到的反应平衡变化归因于反应物质表面附近溶质的积累或消耗。相反，溶质的分配被视为响应表面边界条件而出现的不同水亚群的表现。与所提出的模型一致的热力学框架用于导出两种或多种溶液中特定反应的关系，即水溶解度平衡。由此产生的方程解决了坦福德转移自由能模型的一些潜在问题。讨论了去溶剂化能模型在分析二态蛋白质折叠平衡中的应用，并与 Timasheff 和 Parsegian 开发的其他两种溶质模型的应用进行了对比。未来溶剂化能和大量水能的列表可能使生物物理化学家能够确认次级溶质影响结合和构象平衡的机制，并可能为实验学家和理论学家比较和评估他们的结果提供一个共同基础。
A new phenomenological model for interpreting the effects of solutes on biological equilibria is presented. The model attributes changes in equilibria to differences in the desolvation energy of the reacting species that, in turn, reflect changes in the free energy of the bulk water upon addition of secondary solutes. The desolvation approach differs notably from that of other solute models by treating the free energy of bulk water as a variable and by not ascribing the observed shifts in reaction equilibria to accumulation or depletion of solutes next to the surfaces of the reacting species. On the contrary, the partitioning of solutes is viewed as a manifestation of the different subpopulations of water that arise in response to the surface boundary conditions. A thermodynamic framework consistent with the proposed model is used to derive a relationship for a specific reaction, an aqueous solubility equilibrium, in two or more solutions. The resulting equation reconciles some potential issues with the transfer free energy model of Tanford. Application of the desolvation energy model to the analysis of a two-state protein folding equilibrium is discussed and contrasted to the application of two other solute models developed by Timasheff and by Parsegian. Future tabulation of solvation energies and bulk water energies may allow biophysical chemists to confirm the mechanism by which secondary solutes influence binding and conformational equilibria and may provide a common ground on which experimentalists and theoreticians can compare and evaluate their results.