Abstract

Theoretical analysis of the effect of the ionic strength of a solution on the surface (zeta) potential of liposomes formed by an anionic phospholipid (cardiolipin) with adsorbed polycations has been carried out. The experimental data were previously measured by the electrokinetic method in the presence of polylysine molecules of different molecular weights and a supporting electrolyte, KCl, at concentrations of 10, 40, and 100 mM. To approximate the experimental dependences of the potential on the amount of polylysine in the suspension, we used a theoretical model with parameters, among which the most physically significant are the thickness of the polymer layer, the adsorption constant, and the fraction of the surface of lipid membranes occupied by the polypeptide at the saturation. The found values of the model parameters demonstrate the effect of the length of the polypeptide molecules on the structure of the polymer layer varying from homogeneous to clustered distribution over the surface. A noticeable decrease in the efficiency of adsorption with an increase in the ionic strength of the solution is explained by the conformational rearrangements of the macromolecules on the surface and a decrease in the area of the surface available for their adsorption upon the saturation.

中文翻译：

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离子强度对多肽在脂质膜上吸附的影响：理论分析

摘要

已经对溶液的离子强度对由阴离子磷脂（心磷脂）与吸附的聚阳离子形成的脂质体的表面（zeta）电位的影响进行了理论分析。实验数据先前是在不同分子量的聚赖氨酸分子和支持电解质 KCl 存在下通过电动方法测量的，浓度为 10、40 和 100 mM。为了近似电位对悬浮液中聚赖氨酸量的实验依赖性，我们使用了一个带有参数的理论模型，其中最重要的是聚合物层的厚度、吸附常数和表面的分数。饱和时被多肽占据的脂质膜。模型参数的发现值证明了多肽分子的长度对聚合物层结构的影响，从表面上的均匀分布到成簇分布。随着溶液离子强度的增加，吸附效率的显着降低可以通过表面上大分子的构象重排和饱和时可用于吸附的表面面积减少来解释。