Entropy Drives the Formation of Salt Bridges in the Protein GB3
Entropy Drives the Formation of Salt Bridges in the Protein GB3
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熵驱动蛋白质 GB3 中盐桥的形成
DOI：
10.1002/anie.201702968
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发表时间：
2017
影响因子：
16.6
通讯作者：
Yao Lishan
中科院分区：
文献类型：
--
作者：
Zhang Ning;Wang Yefei;An Liaoyuan;Song Xiangfei;Huang Qingshan;Liu Zhijun;Yao Lishan
盐桥在蛋白质中非常常见。但是什么驱动蛋白质盐桥的形成还不清楚。在这项工作中，我们通过在不同温度下使用高精度NMR滴定法测量构成盐桥的碱性残基的Δ pKa值来确定蛋白质GB3中的四个盐桥的强度。结果表明，Δ pKa值随温度的升高而增大，说明盐桥在较高温度下较强。将Δ pKa值拟合到van't霍夫方程得到正的ΔHand Δ S值，从而表明熵驱动盐桥形成。分子动力学模拟表明，蛋白质和溶剂对ΔHand ΔS的贡献相反.具体地，由蛋白质贡献的熵增益大于由溶剂贡献的熵损失的抵消，而熵增益源自去溶剂化效应。
Salt bridges are very common in proteins. But what drives the formation of protein salt bridges is not clear. In this work, we determined the strength of four salt bridges in the protein GB3 by measuring the ΔpKavalues of the basic residues that constitute the salt bridges with a highly accurate NMR titration method at different temperatures. The results show that the ΔpKavalues increase with temperature, thus indicating that the salt bridges are stronger at higher temperatures. Fitting of ΔpKavalues to the van't Hoff equation yields positive ΔHand ΔSvalues, thus indicating that entropy drives salt‐bridge formation. Molecular dynamics simulations show that the protein and solvent make opposite contributions to ΔHand ΔS. Specifically, the enthalpic gain contributed from the protein is more than offset by the enthalpic loss contributed from the solvent, whereas the entropic gain originates from the desolvation effect.