DeltaG(CH2) as solvent descriptor in polymer/polymer aqueous two-phase systems.
DeltaG(CH2) as solvent descriptor in polymer/polymer aqueous two-phase systems.
复制标题
DOI：
10.1016/j.chroma.2008.01.035
复制
发表时间：
2008-03
期刊：
影响因子：
--
通讯作者：
P. Madeira;J. Teixeira;E. Macedo;L. Mikheeva;B. Zaslavsky
中科院分区：
文献类型：
--
作者：
P. Madeira;J. Teixeira;E. Macedo;L. Mikheeva;B. Zaslavsky
采用不同配对组合的右旋糖酐（Dex-75）、Ficoll-70、聚乙二醇（PEG-8000）、羟丙基淀粉（PES-100）和Ucon50HB5100（乙二醇和丙二醇的随机共聚物），在0.01M磷酸盐缓冲液中，pH为7.4，在23°C条件下形成的水两相体系（atps）的相图。研究了具有脂肪侧链的一系列二硝基苯基氨基酸在特定聚合物浓度下的分配系数。亚甲基在共存相之间的自由转移能ΔG（CH2）被确定为两相疏水特性差异的度量。测定了两相体系中色氨酸（Trp）及其二肽、三肽和一组对硝基苯（NP）单糖的分配系数，并将所得数据与两相体系中的ΔG（CH2）值进行了比较。结果表明，在10个不同聚合物组成的两相体系中，有8个体系的色氨酸肽分配系数与ΔG（CH2）值有很好的相关性。np -单糖的相似相关性在10个两相体系中有7个有效。这些观察结果表明，以ΔG（CH2）值表示的共存相疏水特性之间的差异不能作为比较不同聚合物组成的atps的单一通用度量。
Phase diagrams were determined for aqueous two-phase systems (ATPSs) formed by different paired combinations of Dextran (Dex-75), Ficoll-70, polyethylene glycol (PEG-8000), hydroxypropyl starch (PES-100), and Ucon50HB5100 (a random copolymer of ethylene glycol and propylene glycol) all containing 0.15M NaCl in 0.01M phosphate buffer, pH 7.4, at 23°C. Partition coefficients of a series of dinitrophenylated (DNP) amino acids with aliphatic side-chains were studied in all the ATPSs at particular polymer concentrations. Free energies of transfer of a methylene group between the coexisting phases, ΔG(CH2), were determined as measures of the difference between the hydrophobic character of the phases. Furthermore, partition coefficients of tryptophan (Trp) and its di- and tri-peptides and a set of p-nitrophenyl (NP)-monosaccharides were measured in all the two-phase systems, and the data obtained compared with the ΔG(CH2) values obtained in the systems. It was established that for eight out of 10 of two-phase systems of different polymer compositions the partition coefficients for Trp peptides correlate well with the ΔG(CH2) values. Similar correlations for NP-monosaccharides were valid for seven out of 10 two-phase systems. These observations indicate that the difference between the hydrophobic characters of the coexisting phases represented by the ΔG(CH2) value cannot be used as a single universal measure for comparison of the ATPSs of different polymer compositions.