Phosphatidylcholine exchange between the boundary lipid and bilayer domains in cytochrome oxidase containing membranes.
Phosphatidylcholine exchange between the boundary lipid and bilayer domains in cytochrome oxidase containing membranes.
复制标题
含细胞色素氧化酶的膜中边界脂质和双层结构域之间的磷脂酰胆碱交换。
作者：
P. Jost;K. Nadakavukaren;O. Griffith
磷脂自旋标记，16-羟基磷脂酰胆碱，被用于研究含细胞色素氧化酶膜中的脂质-蛋白质相互作用。两种方法用于标记膜细胞色素氧化酶：分散在胆酸盐中，随后去除洗涤剂，在没有洗涤剂的情况下与纯磷脂标记的囊泡融合。标签的一部分是固定的，计算出其落在0.17- 0.21 mg磷脂/mg蛋白质的范围内（校正未用氯仿-甲醇提取的脂质后为0.15- 0.19）。这个狭窄的范围内的值是独立的方法标记，蛋白质分离，和脂质消耗实验误差。当使用融合标记时，纯磷脂酰胆碱自旋标记的斑块在双分子层平面上扩散，被稀释，并与结合的磷脂进行交换。这些观察结果证明，正如磷脂酰胆碱标签的分配所反映的那样，边界脂质与相邻的双层区域处于平衡状态，并且它由与蛋白质疏水部分相关的相对恒定量的磷脂组成。
A phospholipid spin label, 16-doxylphosphatidylcholine, is employed in a study of lipid--protein interactions in cytochrome oxidase containing membranes. Two methods are used to label the membranous cytochrome oxidase: dispersion in cholate with subsequent detergent removal, and fusion with vesicles of the pure phospholipid label in the absence of detergent. A fraction of the label is immobilized, which is calculated to fall in the range of 0.17--0.21 mg of phospholipid/mg of protein (0.15--0.19 after correction for lipids not extracted by chloroform--methanol). This narrow range of values is independent of methods of labeling, protein isolation, and lipid depletion within experimental error. When labeling by fusion is utilized, the patches of pure phosphatidylcholine spin label diffuse in the plane of the bilayer, become diluted, and demonstrate exchange with bound phospholipid. These observations are evidence that boundary lipid, as reflected by the partitioning of the phosphatidylcholine label, is in equilibrium with adjacent bilayer regions and that it consists of a relatively constant amount of phospholipid associated with the hydrophobic portion of the protein.