Sivars U, Bergfeldt K, Piculell L, Tjerneld F
Department of Biochemistry, Lund University, Sweden.
J Chromatogr B Biomed Appl. 1996 May 17;680(1-2):43-53. doi: 10.1016/0378-4347(95)00564-1.
The study includes partitioning of proteins in aqueous two-phase systems consisting of the polymer dextran and the non-ionic surfactant C12E5 (pentaethylene glycol mono-n-dodecyl ether). In this system a micelle-enriched phase is in equilibrium with a polymer-enriched phase. Charges can be introduced into the micelles by the addition of charged surfactants. The charge of the mixed micelles is easily varied in sign and magnitude independently of pH, by the addition of different amounts of negatively charged surfactant, sodium dodecyl sulphate (SDS), or positively charged surfactant dodecyl trimethyl ammonium chloride (DoTAC). A series of water-soluble model proteins (BSA, beta-lactoglobulin, myoglobin, cytochrome c and lysozyme), with different net charges at pH 7.1, have been partitioned in non-charged systems and in systems with charged mixed micelles or charged polymer (dextran sulphate). It is shown that partition coefficients for charged proteins in dextran-C12E5 systems can be strongly affected by addition of charged surfactants (SDS, DoTAC) or polymer (dextran sulphate) and that the effects are directly correlated to protein net charge.
该研究包括在由聚合物右旋糖酐和非离子表面活性剂C12E5（五乙二醇单正十二烷基醚）组成的水两相系统中对蛋白质进行分配。在这个系统中，富含胶束的相和富含聚合物的相处于平衡状态。通过添加带电表面活性剂可以将电荷引入胶束中。通过添加不同量的带负电表面活性剂十二烷基硫酸钠（SDS）或带正电表面活性剂十二烷基三甲基氯化铵（DoTAC），混合胶束的电荷可以在不依赖于pH值的情况下，轻松地在符号和大小上发生变化。一系列在pH 7.1时具有不同净电荷的水溶性模型蛋白质（牛血清白蛋白、β-乳球蛋白、肌红蛋白、细胞色素c和溶菌酶），已在不带电系统以及带有带电混合胶束或带电聚合物（硫酸右旋糖酐）的系统中进行了分配。结果表明，在右旋糖酐-C12E5系统中，带电蛋白质的分配系数会受到带电表面活性剂（SDS、DoTAC）或聚合物（硫酸右旋糖酐）添加的强烈影响，并且这些影响与蛋白质净电荷直接相关。
