Schluck A, Maurer G, Kula M R
Institut für Enzymtechnologie, Heinrich-Heine-Universitüt Düsseldorf, P.O. Box 2050, D-52404 Jülich, Germany.
Biotechnol Bioeng. 1995 Jul 20;47(2):252-60. doi: 10.1002/bit.260470217.
In aqueous polyethylene glycol/dextran two-phase systems, the hydrophobicity, free volume, surface tension, and interfacial tension of the phases in equilibrium were measured as a function of pH and ionic strength. These parameters were found to change with pH, but the pattern and magnitude cannot explain the unusual partition of charged macromolecules, observed previously. The electrostatic potential difference was determined by a new experimental approach based on the measurement of the pH difference between the phases at equilibrium. In polyethylene glycol/dextran systems containing sodium chloride as ionized species, the electrostatic potential is not constant in the pH range 2 to 11. The partition behavior of charged macromolecules and its dependence on pH can be explained by the combined action of charge and phase potential. This conclusion was tested with poly-L-glutamate, which partitioned as predicted and in a pattern opposite to positively charged macro- molecules. (c) 1995 John Wiley & Sons, Inc.
在水相聚乙二醇/葡聚糖双相体系中，测量了平衡状态下各相的疏水性、自由体积、表面张力和界面张力随pH值和离子强度的变化。发现这些参数随pH值变化，但变化模式和幅度无法解释先前观察到的带电大分子的异常分配。通过一种基于测量平衡状态下各相之间pH值差异的新实验方法确定了静电势差。在含有氯化钠作为离子化物种的聚乙二醇/葡聚糖体系中，静电势在pH值2至11范围内不是恒定的。带电大分子的分配行为及其对pH值的依赖性可以通过电荷和相势的共同作用来解释。用聚-L-谷氨酸对这一结论进行了验证，聚-L-谷氨酸的分配符合预测，且分配模式与带正电的大分子相反。(c) 1995约翰威立父子公司。
