Beyond the Hofmeister Series: Ion-Specific Effects on Proteins and Their Biological Functions
Beyond the Hofmeister Series: Ion-Specific Effects on Proteins and Their Biological Functions
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DOI：
10.1021/acs.jpcb.6b10797
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发表时间：
2017-03-09
影响因子：
3.3
通讯作者：
Jungwirth, Pavel
中科院分区：
文献类型：
--
作者：
Okur, Halil I.;Hladilkova, Jana;Jungwirth, Pavel
离子从溶液中盐出蛋白质的能力不同，表现为溶性或霍夫迈斯特系列阳离子和阴离子。自1888年首次提出以来，该系列已被用于多种效果，超越了最初的盐析/盐析概念，包括酶活性和蛋白质结晶，以及不涉及蛋白质的过程，如离子交换，电解质的表面张力或气泡聚结。虽然已经清楚，Hofmeister系列是密切相关的离子水合在均相和非均相环境和离子配对，其分子起源尚未完全了解。这种情况可以总结如下：许多化学家把霍夫迈斯特系列当作咒语，给各种环境中的离子特异性行为贴上标签，而不是达到分子水平的理解，从而能够预测给定盐离子对溶液中蛋白质的特定影响。在这篇专题文章中，我们表明，阳离子和阴离子霍夫迈斯特系列现在可以主要根据盐离子与溶液中蛋白质表面的主链和带电侧链基团的特定相互作用来合理化。同时，由于电中性条件以及特定的离子配对，我们证明了将霍夫迈斯特效应分离为独立的阳离子和阴离子贡献的局限性，导致极性相反的离子相互作用。最后，我们概述了超越霍夫迈斯特化学的途径，以理解离子在各种生物功能中的特定作用，其中一般的霍夫迈斯特型相互作用可以通过各种离子结合位点的特定空间排列来补充甚至推翻。
Ions differ in their ability to salt out proteins from solution as expressed in the lyotropic or Hofmeister series of cations and anions. Since its first formulation in 1888, this series has been invoked in a plethora of effects, going beyond the original salting out/salting in idea to include enzyme activities and the crystallization of proteins, as well as to processes not involving proteins like ion exchange, the surface tension of electrolytes, or bubble coalescence. Although it has been clear that the Hofmeister series is intimately connected to ion hydration in homogeneous and heterogeneous environments and to ion pairing, its molecular origin has not been fully understood. This situation could have been summarized as follows: Many chemists used the Hofmeister series as a mantra to put a label on ion-specific behavior in various environments, rather than to reach a molecular level understanding and, consequently, an ability to predict a particular effect of a given salt ion on proteins in solutions. In this Feature Article we show that the cationic and anionic Hofmeister series can now be rationalized primarily in terms of specific interactions of salt ions with the backbone and charged side chain groups at the protein surface in solution. At the same time, we demonstrate the limitations of separating Hofmeister effects into independent cationic and anionic contributions due to the electroneutrality condition, as well as specific ion pairing, leading to interactions of ions of opposite polarity. Finally, we outline the route beyond Hofmeister chemistry in the direction of understanding specific roles of ions in various biological functionalities, where generic Hofmeister-type interactions can be complemented or even overruled by particular steric arrangements in various ion binding sites.