Nichols-Smith Stephanie, Kuhl Tonya
Department of Chemical Engineering and Materials Science, University of California, One Shields Avenue, Davis, CA 95616-5294, USA.
Colloids Surf B Biointerfaces. 2005 Mar 25;41(2-3):121-7. doi: 10.1016/j.colsurfb.2004.11.003. Epub 2005 Jan 7.
Lipids are very diverse in both their respective structures and functions; and cells exquisitely control membrane composition. One intriguing issue is the specific role of lipids in modulating the physical properties of membranes. Cardiolipin (CL) is a unique four-tailed, doubly negatively charged lipid found predominately within the inner mitochondrial membrane, and is thought to be influential in determining the inner mitochondrial membrane potential and permeability. To determine the role of cardiolipin in modulating the charge properties of membranes, this study investigated the electrostatic interactions between mixed cardiolipin and phosphatidylcholine bilayers as a function of cardiolipin concentration. For physiologically relevant concentrations of cardiolipin, the surface charge density of the membrane was found to increase linearly with increasing concentration of cardiolipin. However, only a fraction of the cardiolipin molecules predicted to carry a charge from pK-values were ionized. Clearly environmental factors, beyond that of pH, play a role in determining the charge of bilayers containing cardiolipin.
脂质在其各自的结构和功能方面非常多样；细胞能精确地控制膜的组成。一个有趣的问题是脂质在调节膜的物理性质中所起的特定作用。心磷脂（CL）是一种独特的具有四条尾巴、带两个负电荷的脂质，主要存在于线粒体内膜中，并且被认为对决定线粒体内膜电位和通透性有影响。为了确定心磷脂在调节膜电荷性质中的作用，本研究调查了混合的心磷脂和磷脂酰胆碱双层膜之间的静电相互作用与心磷脂浓度的关系。对于生理相关浓度的心磷脂，发现膜的表面电荷密度随心磷脂浓度的增加呈线性增加。然而，根据pK值预测应带电荷的心磷脂分子中只有一部分发生了电离。显然，除了pH之外，环境因素在决定含有心磷脂的双层膜的电荷方面也发挥着作用。
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