Wiegel D, Richter O, Arnold K
University of Leipzig, School of Medicine, Institute of Medical Physics and Biophysics, Germany.
J Chromatogr A. 1994 May 6;668(1):107-16. doi: 10.1016/0021-9673(94)80098-7.
Aqueous polyethylene glycol (PEG)-dextran two-phase systems containing 10 mM Tris.HCl (pH 7.4) were used for the partitioning of chemically modified low-density lipoprotein (LDL). Anionic modification connected with an increase in the negative surface charge of lipoproteins favours the accumulation of modified LDL in the top phase. The partition coefficient increases depending on the extent of modification. Cationic modification yields lower values for the partition coefficient. Positively charged LDL favours a bottom-phase accumulation. With weakly charged and nearly neutral particles, the Van der Waals interaction between polymer and particle preponderates over electrostatic interactions, leading to a favoured accumulation of LDL in the PEG-rich top phase. Results of measurements of the relative electrophoretic mobility and the determination of free amino groups are in agreement with the calculated values of the partition coefficient. Because the partitioning of LDL is accompanied by aggregation at the interface, experimental techniques have to be carefully standardized. Subtle differences in the surface properties of modified LDL can be detected.
含有10 mM Tris.HCl（pH 7.4）的水性聚乙二醇（PEG）-葡聚糖双相系统用于化学修饰的低密度脂蛋白（LDL）的分配。与脂蛋白表面负电荷增加相关的阴离子修饰有利于修饰的LDL在上相中积累。分配系数根据修饰程度而增加。阳离子修饰产生较低的分配系数值。带正电荷的LDL有利于在下相中积累。对于带弱电荷和接近中性的颗粒，聚合物与颗粒之间的范德华相互作用超过静电相互作用，导致LDL在富含PEG的上相中优先积累。相对电泳迁移率的测量结果和游离氨基的测定结果与分配系数的计算值一致。由于LDL的分配伴随着界面处的聚集，因此实验技术必须仔细标准化。可以检测到修饰的LDL表面性质的细微差异。
