McLaughlin S G, Szabo G, Eisenman G, Ciani S M
Proc Natl Acad Sci U S A. 1970 Nov;67(3):1268-75. doi: 10.1073/pnas.67.3.1268.
Bilayer membranes, formed from various phospholipids, were studied to assess the influence of the charge of the polar head groups on the membrane conductance mediated by neutral "carriers" of cations and anions. The surface charge of an amphoteric lipid, phosphatidyl ethanolamine, was altered by varying the pH, and the surface charge of several lipids was screened by increasing the ionic strength of the solution with impermeant monovalent and divalent electrolytes. The surface charge should be a key parameter in defining the membrane conductance for a variety of permeation mechanisms; conductance measurements in the presence of carriers may be used to estimate the potential difference, due to surface charge, between the interior of the bilayer and the bulk aqueous phase. The large changes in conductance observed upon varying the surface charge density and the ionic strength agree with those predicted by the Gouy-Chapman theory for an aqueous diffuse double layer. Explicit expressions for the dependence of the membrane conductance on the concentrations of the carrier, the permeant ion, the surface charge density, and the ionic strength are presented.
研究了由各种磷脂形成的双层膜，以评估极性头部基团的电荷对由阳离子和阴离子的中性“载体”介导的膜电导的影响。通过改变pH值来改变两性脂质磷脂酰乙醇胺的表面电荷，并通过用非渗透性单价和二价电解质增加溶液的离子强度来筛选几种脂质的表面电荷。表面电荷应该是定义各种渗透机制的膜电导的关键参数；在存在载体的情况下进行的电导测量可用于估计由于表面电荷导致的双层内部与本体水相之间的电位差。在改变表面电荷密度和离子强度时观察到的电导的巨大变化与古伊-查普曼理论对水性扩散双层的预测一致。给出了膜电导对载体浓度、渗透离子浓度、表面电荷密度和离子强度的依赖性的明确表达式。
