Competitive Counterion Binding Regulates the Aggregation Onset of Vimentin Intermediate Filaments
Competitive Counterion Binding Regulates the Aggregation Onset of Vimentin Intermediate Filaments
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DOI：
10.1002/ijch.201400153
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发表时间：
2016-08-01
影响因子：
3.2
通讯作者：
Koester, Sarah
中科院分区：
文献类型：
--
作者：
Dammann, Christian;Herrmann, Harald;Koester, Sarah
聚集是混合带电生物聚合物和抗衡离子时常见的现象。然而，找到所涉及机制的一般描述仍然是一个挑战。在这里，我们研究了波形蛋白中间丝，它总体上带有高负电荷，作为此类生物聚电解质的一个主要例子。我们通过实验确定了聚集的起始阳离子浓度，并将其与计算的长丝表面附近的相对阳离子浓度相关联。我们的分析表明，为了实现聚集，最初存在的约 50% 的单价阳离子必须被二价或多价阳离子取代。因此，我们能够预测大量阳离子浓度，该浓度介导带高负电荷的波形蛋白丝的聚集。
Aggregation is a commonly observed phenomenon when mixing charged biopolymers and counterions. However, it remains a challenge to find a general description for the involved mechanisms. Here, we investigate vimentin intermediate filaments, which are overall highly negatively charged, as a prime example of such biological polyelectrolytes. We experimentally determine the onset cation concentration for aggregation, and set it in relation to the calculated relative cation concentrations in the vicinity of the filament surface. Our analysis shows that to achieve aggregation, about 50% of the monovalent cations originally present have to be replaced by di- or multivalent cations. We are thus able to predict the bulk cation concentration, which mediates aggregation of highly negatively charged vimentin filaments.