Diffusion and Partitioning of Fluorescent Lipid Probes in Phospholipid Monolayers
Diffusion and Partitioning of Fluorescent Lipid Probes in Phospholipid Monolayers
复制标题
DOI：
10.1016/j.bpj.2009.01.063
复制
发表时间：
2009-06-03
影响因子：
3.4
通讯作者：
Heimburg, T.
中科院分区：
文献类型：
--
作者：
Gudmand, M.;Fidorra, Matthias;Heimburg, T.
使用定制的单层槽安装在一个组合的荧光相关光谱（FCS）和宽视场显微镜设置的DMPC和DPPC单层的压力依赖性扩散和分配的单一脂质荧光团进行了研究。它表明，脂质扩散，这是必不可少的生物膜的功能，是严重影响的侧向压力和相的脂质结构。这两者都可以在例如，蛋白质吸附和解吸过程。使用FCS，我们测量了在DMPC单分子膜的侧向压力在很宽的范围内的脂质扩散系数，并将它们拟合到自由面积模型以及直接实验观察到的平均分子面积。还在低于相变开始时（Pi < 5 mN/m）对DPPC单层进行FCS测量。在较高的压力下，FCS不适用于测量DPPC单层中的扩散系数。单分子荧光显微镜和差示扫描量热法清楚地表明，这是由于在凝聚相中的脂质荧光团的非均匀分配。的结果进行了比较与染料分配在巨大的脂质囊泡。这些发现是重要的脂质荧光团的应用研究扩散在模型系统和生物系统。
The pressure-dependent diffusion and partitioning of single lipid fluorophores in DMPC and DPPC monolayers were investigated with the use of a custom-made monolayer trough mounted on a combined fluorescence correlation spectroscopy (FCS) and wide-field microscopy setup. It is shown that lipid diffusion, which is essential for the function of biological membranes, is heavily influenced by the lateral pressure and phase of the lipid structure. Both of these may change dynamically during, e.g., protein adsorption and desorption processes. Using FCS, we measured lipid diffusion coefficients over a wide range of lateral pressures in DMPC monolayers and fitted them to a free-area model as well as the direct experimental observable mean molecular area. FCS measurements on DPPC monolayers were also performed below the onset of the phase transition (Pi < 5 mN/m). At higher pressures, FCS was not applicable for measuring diffusion coefficients in DPPC monolayers. Single-molecule fluorescence microscopy and differential scanning calorimetry clearly showed that this was due to heterogeneous partitioning of the lipid fluorophores in condensed phases. The results were compared with dye partitioning in giant lipid vesicles. These findings are significant in relation to the application of lipid fluorophores to study diffusion in both model systems and biological systems.