Model binding experiments with cucurbit[7]uril and p-sulfonatocalix[4]arene support use of explicit solvation term in governing equation for binding equilibria
Model binding experiments with cucurbit[7]uril and p-sulfonatocalix[4]arene support use of explicit solvation term in governing equation for binding equilibria
复制标题
DOI：
10.1080/10610278.2023.2254442
复制
发表时间：
2023-09-04
影响因子：
3.3
通讯作者：
Shao, Kevin
中科院分区：
文献类型：
--
作者：
Eggers, Daryl K.;Brewer, Adam;Shao, Kevin
用等温滴定量热法对模型主客体结合反应的热力学进行了深入研究。与经典热力学不一致的是，结果表明，平衡结合商K不是所有配对的常数。这一结果是由结合平衡方程预测的，该方程包括一个显式项，表示伴随着二元络合物的形成的溶剂化自由能的变化。将这一框架应用于实验观察到的K的浓度依赖关系，使人们能够获得溶剂的能量贡献，一个连接的平衡在这里表示为增量G(H2O)。DELTA G(H2O)的估计值很大，不利于选定的客体分子与两个主体--瓜环和对磺酸基杯[4]芳烃的结合。有趣的是，两个疏水客体分子与ss-环糊精结合时，Delta G(H2O)的估计值接近于零，这引发了一场关于疏水效应背后驱动力的发人深省的讨论。
The thermodynamics of model host-guest-binding reactions is examined in depth using isothermal titration calorimetry. In conflict with classical thermodynamics, the results indicate that the equilibrium-binding quotient, K, is not a constant for all pairings. This outcome is predicted by an equation for binding equilibria that includes an explicit term for the change in solvation free energy that accompanies the formation of a binary complex. Application of this framework to the experimentally observed concentration dependence of K allows one to obtain the energetic contribution of the solvent, a linked equilibrium denoted here as Delta G(H2O). The estimated values of Delta G(H2O) are large and unfavourable for the binding of selected guest molecules to two hosts, cucurbit[7]uril and p-sulfonatocalix[ 4]arene. Intriguingly, the estimated values of Delta G(H2O) are near zero for the binding of two hydrophobic guest molecules to ss-cyclodextrin, leading to a thought-provoking discussion on the driving force behind the hydrophobic effect.[GRAPHICS.]