Ferreira Luisa, Madeira Pedro P, Mikheeva Larissa, Uversky Vladimir N, Zaslavsky Boris
AnalizaDx Inc., 3615 Superior Ave., Suite 4407B, Cleveland, OH 44114, USA.
Biochim Biophys Acta. 2013 Dec;1834(12):2859-66. doi: 10.1016/j.bbapap.2013.07.014. Epub 2013 Aug 3.
Partitioning of 15 proteins in polyethylene glycol (PEG)-sodium sulfate aqueous two-phase systems (ATPS) formed by PEG of two different molecular weights, PEG-600 and PEG-8000 in the presence of different buffers at pH7.4 was studied. The effect of two salt additives (NaCl and NaSCN) on the protein partition behavior was examined. The salt effects on protein partitioning were analyzed by using the Collander solvent regression relationship between the proteins partition coefficients in ATPS with and without salt additives. The results obtained show that the concentration of buffer as well as the presence and concentration of salt additives affects the protein partition behavior. Analysis of ATPS in terms of the differences between the relative hydrophobicity and electrostatic properties of the phases does not explain the protein partition behavior. The differences between protein partitioning in PEG-600-salt and PEG-8000-salt ATPS cannot be explained by the protein size or polymer excluded volume effect. It is suggested that the protein-ion and protein-solvent interactions in the phases of ATPS are primarily important for protein partitioning.
研究了在pH7.4的不同缓冲液存在下，由两种不同分子量的聚乙二醇（PEG），即PEG - 600和PEG - 8000形成的聚乙二醇 - 硫酸钠水相双相系统（ATPS）中15种蛋白质的分配情况。考察了两种盐添加剂（NaCl和NaSCN）对蛋白质分配行为的影响。利用有无盐添加剂时蛋白质在ATPS中的分配系数之间的科兰德溶剂回归关系，分析了盐对蛋白质分配的影响。所得结果表明，缓冲液浓度以及盐添加剂的存在和浓度会影响蛋白质的分配行为。从各相相对疏水性和静电性质的差异角度对ATPS进行分析，并不能解释蛋白质的分配行为。蛋白质在PEG - 600 - 盐和PEG - 8000 - 盐ATPS中的分配差异，无法用蛋白质大小或聚合物排除体积效应来解释。研究表明，ATPS各相中蛋白质 - 离子和蛋白质 - 溶剂相互作用对蛋白质分配至关重要。
