How Hofmeister ion interactions affect protein stability
How Hofmeister ion interactions affect protein stability
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DOI：
10.1016/s0006-3495(96)79404-3
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发表时间：
1996-10-01
影响因子：
3.4
通讯作者：
Baldwin, RL
中科院分区：
文献类型：
--
作者：
Baldwin, RL
文献中的模型化合物研究表明霍夫迈斯特离子相互作用如何影响蛋白质的稳定性。虽然模型化合物的结果通常是盐析常数，但它们可以用来找出相互作用如何影响蛋白质的稳定性。在区分蛋白质变性剂和稳定剂的霍夫迈斯特系列中，零点来自与不同类别基团的相反相互作用：霍夫迈斯特离子盐析出非极性基团和多肽基团中的盐。霍夫迈斯特离子相互作用如何工作的理论需要从解释这两类相互作用的机制开始。盐析非极性基团可以用空穴模型来解释，但它的使用存在争议。当应用于模拟化合物数据时，腔模型1)使用表面张力增量来预测盐析常数的观测值，系数为3，以及2)预测盐析常数应该随着观察到的氨基酸的脂肪侧链中的碳原子的数量而增加。Hofmeister离子与多肽之间的相互作用机制尚不清楚，这种相互作用是离子特异性的，还是非特异性的，以及这种明显的特异性存在于与附近非极性基团的相互作用中，这一点存在争议。已知在简单离子和偶极分子之间发生非特定的盐析相互作用；它取决于离子强度，而不是霍夫迈斯特系列中的位置。Kirkwood的理论预测了这种相互作用的强度，并指出它取决于离子强度的一次幂，除了这里讨论的Hofmeister离子相互作用外，离子与蛋白质以各种方式相互作用，特别是通过电荷相互作用。人们对这些相互作用的了解大多来自Serge Timasheff和他的同事的研究。记录和同事的双域模型提供了一个适用于分析不同离子-蛋白质相互作用的通用模型。
Model compound studies in the literature show how Hofmeister ion interactions affect protein stability. Although model compound results are typically obtained as salting-out constants, they can be used to find out how the interactions affect protein stability. The null point in the Hofmeister series, which divides protein denaturants from stabilizers, arises from opposite interactions with different classes of groups: Hofmeister ions salt out nonpolar groups and salt in the peptide group. Theories of how Hofmeister ion interactions work need to begin by explaining the mechanisms of these two classes of interactions. Salting-out nonpolar groups has been explained by the cavity model, but its use is controversial. When applied to model compound data, the cavity model 1) uses surface tension increments to predict the observed values of the salting-out constants, within a factor of 3, and 2) predicts that the salting-out constant should increase with the number of carbon atoms in the aliphatic side chain of an amino acid, as observed. The mechanism of interaction between Hofmeister ions and the peptide group is not well understood, and it is controversial whether this interaction is ion-specific, or whether it is nonspecific and the apparent specificity resides in interactions with nearby nonpolar groups. A nonspecific salting-in interaction is known to occur between simple ions and dipolar molecules; it depends on ionic strength, not on position in the Hofmeister series. A theory by Kirkwood predicts the strength of this interaction and indicates that it depends on the first power of the ionic strength, ions interact with proteins in various ways besides the Hofmeister ion interactions discussed here, especially by charge interactions. Much of what is known about these interactions comes from studies by Serge Timasheff and his co-workers. A general model, suitable for analyzing diverse ion-protein interactions, is provided by the two-domain model of Record and co-workers.