On the localization of ubiquinone in phosphatidylcholine bilayers.
On the localization of ubiquinone in phosphatidylcholine bilayers.
复制标题
关于泛醌在磷脂酰胆碱双层中的定位。
DOI：
10.1016/0005-2728(84)90040-9
复制
发表时间：
1984
期刊：
影响因子：
--
通讯作者：
Siedow,JN
中科院分区：
文献类型：
--
作者：
Stidham,MA;McIntosh,TJ;Siedow,JN
使用多种物理技术分析了磷脂双层中泛醌 10 的位置。具体来说，我们检验了泛醌位于磷脂双层的几何中心的假设。在室温下，在存在 0.05-0.5 摩尔分数的泛醌的情况下，二棕榈酰磷脂酰胆碱的光学显微镜显示出两个独立的相，一个是双折射层状相，另一个是由各向同性液滴组成的相。各向同性相具有明显的黄色，这是熔化的泛醌的特征。含有添加泛醌的磷脂酰胆碱脂质体的[13C]NMR光谱表明对双层极性头部区域附近的脂烃链原子的13C自旋晶格弛豫时间有显着影响，但对最接近双层中心的那些原子几乎没有影响。 X射线衍射实验表明，对于磷脂酰胆碱双层，无论是在凝胶相还是液晶相中，泛醌的存在都不会改变层状重复周期或脂烃链的广角反射。在电子显微照片中，波纹（Pβ'）相双层的疏水性冷冻断裂表面也未因泛醌的存在而改变。这些结果表明，分配到双层中的泛醌并不优先位于单层之间，并且相当一部分泛醌形成位于脂质双层外部的单独相。
The location of ubiquinone-10 in phospholipid bilayers was analyzed using a variety of physical techniques. Specifically, we examined the hypothesis that ubiquinone localizes at the geometric center of phospholipid bilayers. Light microscopy of dipalmitoylphosphatidylcholine at room temperature in the presence of 0.05–0.5 mol fraction ubiquinone showed two separate phases, one birefringent lamellar phase and one phase that consisted of isotropic liquid droplets. The isotropic phase had a distinct yellow color, characteristic of melted ubiquinone. [13C]NMR spectroscopy of phosphatidylcholine liposomes containing added ubiquinone indicated a marked effect on the13C-spin lattice relaxation times of the lipid hydrocarbon chain atoms near the polar head region of the bilayer, but almost no effect on those atoms nearest the center of the bilayer. X-ray diffraction experiments showed that for phosphatidylcholine bilayers, both in the gel and liquid-crystal-line phases, the presence of ubiquinone did not change either the lamellar repeat period or the wide-angle reflections from the lipid hydrocarbon chains. In electron micrographs, the hydrophobic freeze-fracture surfaces of bilayers in the rippled (Pβ′) phase were also unmodified by the presence of ubiquinone. These results indicate that the ubiquinone which does partition into the bilayer is not localized preferentially between the monolayers, and that an appreciable fraction of the ubiquinone forms a separate phase located outside the lipid bilayer.