We revisit the charge-regulation mechanism of macro-ions and apply it to mobile macro-ions in a bathing salt solution. In particular, we examine the effects of correlation between various adsorption/desorption sites and analyze the collective behavior in terms of the solution effective screening properties. We show that such a behavior can be quantified in terms of the charge asymmetry of the macro-ions, defined by their preference for a non-zero effective charge, and their donor/acceptor propensity for exchanging salt ions with the bathing solution. Asymmetric macro-ions tend to increase the screening, while symmetric macro-ions can in some cases decrease it. Macro-ions that are classified as donors display a rather regular behavior, while those that behave as acceptors exhibit an anomalous non-monotonic Debye length. The screening properties, in their turn, engender important modifications to the disjoining pressure between two charged surfaces. Our findings are in particular relevant for solutions of proteins, whose exposed amino acids can undergo charge dissociation/association processes to/from the bathing solution, and can be considered as a solution of charged regulated macro-ions, as analyzed here.

中文翻译：

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盐溶液中的电荷调节性大离子：筛选性质和静电相互作用

我们重新审视大离子的电荷调节机制，并将其应用于沐浴盐溶液中的移动大离子。特别是，我们检查了各种吸附/解吸位点之间的相关性影响，并根据溶液的有效筛选特性分析了其集体行为。我们表明，可以根据大离子的电荷不对称性（由其对非零有效电荷的偏好以及其供体/受体来定义）来量化这种行为与沐浴液交换盐离子的倾向。不对称的大离子往往会增加筛选，而对称的大离子在某些情况下会降低筛选。被分类为供体的大分子离子表现出相当规则的行为，而作为受体的大分子离子表现出异常的非单调德拜长度。筛选性质又对两个带电表面之间的分离压力进行了重要的修改。我们的发现特别适用于蛋白质溶液，其暴露的氨基酸可以经过与进水溶液的离解/缔合过程，并且可以视为带电荷的调节大离子的溶液（如此处分析）。