Abstract：
Cholesterol in a bio-membrane plays a significant role in many cellular event and is known to regulate the functional activity of protein and ion channel. In this study we report a significant effect of cholesterol on the ion-membrane interaction. We prepare large unilamellar vesicles, composed of zwitterionic lipid DOPC and anionic lipid DOPG with different cholesterol concentration. Electrostatics of anionic membranes containing cholesterol in the presence of NaCl has systematically been explored using dynamic light scattering and zeta potential. Negative zeta potential of the membrane decreases its negative value with increasing ion concentration for all cholesterol concentrations. However, zeta potential itself decreases with increasing cholesterol content even in the absence of monovalent ions. Electrostatic behaviour of the membrane is determined from well-known Gouy Chapmann model. Negative surface charge density of the membrane decreases with increasing cholesterol content. Binding constant, estimated from the electrostatic double layer theory, is found to increase significantly in the presence of cholesterol. Comparison of electrostatic parameters of the membrane in the presence and absence of cholesterol suggests that cholesterol significantly alter the electrostatic behaviour of the membrane.
摘要：
生物膜中的胆固醇在许多细胞事件中起着重要作用，并且已知调节蛋白质和离子通道的功能活性。在这项研究中，我们报告了胆固醇对离子膜相互作用的显着影响。我们准备大的单层囊泡，由不同胆固醇浓度的两性离子脂质DOPC和阴离子脂质DOPG组成。已使用动态光散射和ζ电位系统地研究了在NaCl存在下含有胆固醇的阴离子膜的静电。对于所有胆固醇浓度，膜的负ζ电位随着离子浓度的增加而降低其负值。然而,即使在不存在单价离子的情况下，ζ电位本身也会随着胆固醇含量的增加而降低。膜的静电行为由众所周知的GouyChapmann模型确定。膜的负表面电荷密度随着胆固醇含量的增加而降低。绑定常数,根据静电双层理论估计，发现在胆固醇存在下显着增加。在存在和不存在胆固醇的情况下膜的静电参数的比较表明,胆固醇显著改变膜的静电行为。
