Kahya Nicoletta, Schwille Petra
Institute of Biophysics, Biotechnology Center, Dresden University of Technology, Tatzberg 47-49, D-01307 Dresden, Germany.
J Fluoresc. 2006 Sep;16(5):671-8. doi: 10.1007/s10895-006-0108-6. Epub 2006 Aug 1.
Cholesterol is a key player in regulating physico-chemical properties of cellular membranes and, thereby, ensuring cell viability. In particular, lipid-cholesterol interactions may provide important information on the spatio-temporal organization of membrane components. Here, we apply confocal imaging and Fluorescence Correlation Spectroscopy (FCS) to Giant Unilamellar Vesicles (GUVs) composed of binary mixtures of lipids and cholesterol. The effect of cholesterol on lipid dynamics and molecular packing order of unsaturated, monounsaturated, fully saturated (with both low and high phase transition temperatures, Tm) glycero-phospholipids and sphingomyelin has been investigated. We show that, for unsaturated glycerophospholipids, the decrease of the lipid diffusion coefficient as a result of the interaction with cholesterol does not depend on the fatty acid chain length. However, the values of the diffusion coefficient change as a function of chain length. The monounsaturated phospholipid palmitoyl-oleoyl-phosphatidylcholine (POPC) exhibits a dynamic behavior very similar to the unsaturated dioleoyl-phosphatidylcholine (DOPC). By contrast, for saturated (low Tm) glycero-phospholipids, cholesterol causes a decrease of lipid mobility in a chain length-dependent manner. FCS can be employed as a valuable tool to study lipid-sterol interactions and their effect on lipid dynamics, molecular packing and degree of conformational order.
胆固醇是调节细胞膜物理化学性质从而确保细胞活力的关键因素。特别是,脂质 - 胆固醇相互作用可能为膜成分的时空组织提供重要信息。在此,我们将共聚焦成像和荧光相关光谱法(FCS)应用于由脂质和胆固醇的二元混合物组成的巨型单层囊泡(GUVs)。研究了胆固醇对不饱和、单不饱和、完全饱和(具有低和高相变温度,Tm)甘油磷脂和鞘磷脂的脂质动力学和分子堆积顺序的影响。我们表明,对于不饱和甘油磷脂,与胆固醇相互作用导致的脂质扩散系数降低不取决于脂肪酸链长度。然而,扩散系数的值随链长度而变化。单不饱和磷脂棕榈酰 - 油酰 - 磷脂酰胆碱(POPC)表现出与不饱和二油酰 - 磷脂酰胆碱(DOPC)非常相似的动态行为。相比之下,对于饱和(低Tm)甘油磷脂,胆固醇以链长度依赖的方式导致脂质流动性降低。FCS可作为研究脂质 - 甾醇相互作用及其对脂质动力学、分子堆积和构象有序度影响的有价值工具。