Protein Stabilization and Enzyme Activation in Ionic Liquids: Specific Ion Effects.
Protein Stabilization and Enzyme Activation in Ionic Liquids: Specific Ion Effects.
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DOI：
10.1002/jctb.4837
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发表时间：
2016-01
期刊：
影响因子：
--
通讯作者：
Zhao H
中科院分区：
文献类型：
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作者：
Zhao H
关于离子的水合作用是否会扰乱水的结构以及这种扰动的程度如何，仍然存在争议。因此，霍夫迈斯特效应对蛋白质稳定性的起源仍然受到质疑。因此，建议使用“特定离子效应”，而不是其他误导性术语，例如霍夫迈斯特效应、霍夫迈斯特级数、溶致效应和溶致级数。在这篇综述中，我们首先讨论无机离子对水结构影响的争议方面，以及蛋白质稳定性的特定离子效应的几个可能的贡献者。由于最近离子液体（IL）作为良性溶剂在许多酶促反应中具有压倒性的吸引力，我们进一步评估了纯离子液体及其水溶液的结构特性和分子水平相互作用。接下来，我们系统地比较了 IL 的特异性离子对酶稳定性和活性的影响，并得出结论：（a）稀释的 IL 水溶液中许多酶系统的特异性大致与传统的 Hofmeister 系列一致，尽管有一些例外； (b) 然而，由于其他因素（如氢键碱性、亲核性和疏水性等）起着主导作用，因此浓缩或纯离子液体的特异性遵循不同的轨迹。此外，我们还展示了 IL 系统中受经验特异性规则指导的生物催化反应的一些示例。
There are still debates on whether the hydration of ions perturbs the water structure, and what is the degree of such disturbance; therefore, the origin of Hofmeister effect on protein stabilization continues being questioned. For this reason, it is suggested to use the ‘specific ion effect’ instead of other misleading terms such as Hofmeister effect, Hofmeister series, lyotropic effect, and lyotropic series. In this review, we firstly discuss the controversial aspect of inorganic ion effects on water structures, and several possible contributors to the specific ion effect of protein stability. Due to recent overwhelming attraction of ionic liquids (ILs) as benign solvents in many enzymatic reactions, we further evaluate the structural properties and molecular-level interactions in neat ILs and their aqueous solutions. Next, we systematically compare the specific ion effects of ILs on enzyme stability and activity, and conclude that (a) the specificity of many enzymatic systems in diluted aqueous IL solutions is roughly in line with the traditional Hofmeister series albeit some exceptions; (b) however, the specificity follows a different track in concentrated or neat ILs because other factors (such as hydrogen-bond basicity, nucelophilicity, and hydrophobicity, etc) are playing leading roles. In addition, we demonstrate some examples of biocatalytic reactions in IL systems that are guided by the empirical specificity rule.