Díaz-Tejada Celsa, Ariz-Extreme Igor, Awasthi Neha, Hub Jochen S
Georg-August-University Göttingen , Institute for Microbiology and Genetics, Justus-von-Liebig-Weg 11, 37077 Göttingen, Germany.
J Phys Chem Lett. 2015 Dec 3;6(23):4799-803. doi: 10.1021/acs.jpclett.5b02414. Epub 2015 Nov 20.
Lateral inhomogeneity plays a critical role for many properties of cholesterol-containing membranes, yet the thermodynamic forces involved in inhomogeneity remain poorly understood. Based on coarse-grained simulations of cholesterol in four increasingly unsaturated phospholipids, we computed lateral density fluctuations and free energies of domain formation, and we quantitatively relate those to variations in the chemical potential of cholesterol. Our simulations suggest that the lateral organization is dominated by weak repulsive cholesterol interactions, leading to a significantly more homogeneous distribution as compared to a two-dimensional ideal gas. Hence, phospholipids provide a "good" solvent for cholesterol. Unexpectedly, the degree of unsaturation of the phospholipid has only a minor effect on the lateral inhomogeneity of cholesterol in binary lipid mixtures. These results provide a link between functional properties and thermal fluctuations in lipid membranes.
横向不均匀性对含胆固醇膜的许多性质起着关键作用，但不均匀性所涉及的热力学力仍知之甚少。基于对四种不饱和程度逐渐增加的磷脂中胆固醇的粗粒度模拟，我们计算了横向密度涨落和畴形成的自由能，并将这些与胆固醇化学势的变化定量关联起来。我们的模拟表明，横向组织由弱的排斥性胆固醇相互作用主导，与二维理想气体相比，导致分布显著更均匀。因此，磷脂为胆固醇提供了一种“良好”的溶剂。出乎意料的是，磷脂的不饱和程度对二元脂质混合物中胆固醇的横向不均匀性只有轻微影响。这些结果在脂质膜的功能性质和热涨落之间建立了联系。
