CALCULATIONS OF THE ELECTROSTATIC POTENTIAL ADJACENT TO MODEL PHOSPHOLIPID-BILAYERS
CALCULATIONS OF THE ELECTROSTATIC POTENTIAL ADJACENT TO MODEL PHOSPHOLIPID-BILAYERS
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DOI：
10.1016/s0006-3495(95)80253-5
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发表时间：
1995-03-01
影响因子：
3.4
通讯作者：
MCLAUGHLIN, S
中科院分区：
文献类型：
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作者：
PEITZSCH, RM;EISENBERG, M;MCLAUGHLIN, S
我们用非线性Poisson-Boltzmann方程计算了含有两性离子脂类(磷脂酰胆碱)和酸性脂类(磷脂酰丝氨酸或磷脂酰甘油)混合物的模型磷脂双层邻近水相中的静电势。水相(相对介电常数，epsilon(R)=80)含有0.1M的单价盐。当双分子层中含有25%的酸性脂类时，-25 mV等电势分布基本平坦，与Gouy-Chapman理论计算的值符合得很好。当双层含有100%的酸性类脂时，所有的等势面都是平坦的，并符合Gouy-Chapman的预测(包括-100 mV的表面，它距离最外面的原子只有1埃)。即使我们的模型双层也不是简单的系统：每个脂质上的电荷分布在几个原子上，这些部分电荷是非共面的，在极性头基附近有一个2埃离子排斥区域(epsilon(R)=80)，分子表面很粗糙。我们用嵌入了点电荷的光滑(或凹凸不平)epsilon(R)=2平板研究了这四个因素的影响：这些因素对水相中的电势影响很小。
We used the nonlinear Poisson-Boltzmann equation to calculate electrostatic potentials in the aqueous phase adjacent to model phospholipid bilayers containing mixtures of zwitterionic lipids (phosphatidylcholine) and acidic lipids (phosphatidylserine or phosphatidylglycerol). The aqueous phase (relative permittivity, epsilon(r) = 80) contains 0.1 M monovalent salt. When the bilayers contain 25% acidic lipid, the -25 mV equipotential profiles are essentially flat and agree well with the values calculated using Gouy-Chapman theory. When the bilayers contain 100% acidic lipid, all of the equipotential surfaces are flat and agree with Gouy-Chapman predictions (including the -100 mV surface, which is located only 1 Angstrom from the outermost atoms). Even our model bilayers are not simple systems: the charge on each lipid is distributed over several atoms, these partial charges are non-coplanar, there is a 2 Angstrom ion-exclusion region (epsilon(r) = 80) adjacent to the polar headgroups, and the molecular surface is rough. We investigated the effect of these four factors using smooth (or bumpy) epsilon(r) = 2 slabs with embedded point charges: these factors had only minor effects on the potential in the aqueous phase.