Okur Halil I, Hladílková Jana, Rembert Kelvin B, Cho Younhee, Heyda Jan, Dzubiella Joachim, Cremer Paul S, Jungwirth Pavel
Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), School of Engineering (STI), École Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland.
Institute of Organic Chemistry and Biochemistry, The Czech Academy of Sciences , Flemingovo nam. 2, 16610 Prague 6, Czech Republic.
J Phys Chem B. 2017 Mar 9;121(9):1997-2014. doi: 10.1021/acs.jpcb.6b10797. Epub 2017 Feb 8.
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.
离子从溶液中盐析蛋白质的能力各不相同，这在溶致或霍夫迈斯特阳离子和阴离子序列中有所体现。自1888年首次提出以来，该序列已被用于解释大量的效应，其范围超出了最初的盐析/盐溶概念，涵盖了酶活性、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并。尽管很明显霍夫迈斯特序列与均相和非均相环境中的离子水合以及离子配对密切相关，但其分子起源尚未完全理解。这种情况可以总结如下：许多化学家将霍夫迈斯特序列当作一种口头禅，用于给各种环境中离子特异性行为贴上标签，而不是达到分子层面的理解，进而能够预测给定盐离子对溶液中蛋白质的特定效应。在这篇专题文章中，我们表明，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，来合理解释阳离子和阴离子霍夫迈斯特序列。同时，我们证明了由于电中性条件以及特定离子配对导致相反极性离子之间的相互作用，将霍夫迈斯特效应分离为独立的阳离子和阴离子贡献存在局限性。最后，我们概述了超越霍夫迈斯特化学的途径，朝着理解离子在各种生物功能中的特定作用的方向发展，在各种离子结合位点中，一般的霍夫迈斯特型相互作用可能会被特定的空间排列所补充甚至推翻。
