School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 315 Ferst Drive, Atlanta, Georgia 30332-0363, USA.
J Phys Chem B. 2010 Apr 1;114(12):4383-7. doi: 10.1021/jp912126w.
This paper compares two manifestations of electrolyte-mediated interaction between globular proteins. Salt-induced protein aggregation is studied with dynamic light scattering (DLS) in solutions of lysozyme and bovine serum albumin (BSA) containing different types of sodium salts. The same types of ions are used in a second measurement series assessing the effect of more dilute electrolytes on protein diffusivity in non-aggregating protein dispersions. Both aggregation and stable diffusion exhibit strong ion specificity along the lines of the Hofmeister series: chaotropic counterions act as the strongest coagulants and, in stable protein solutions, lead to the lowest "protein interaction parameter", evaluated as the slope of protein diffusivity versus protein concentration. Within this common qualitative trend, lysozyme and BSA solutions show marked differences, including the sign of the interaction parameter for most of the tested solution compositions. Despite the different nature of lysozyme and BSA, a strong correlation is found in both cases between the ion-specific interaction parameter and the proteins' aggregation tendency as indicated by the salt concentration required for fast aggregation. The interaction parameter, available via quick and easy DLS measurements on stable protein solutions, may thus serve as a predictor of ion-specific aggregation trends.
本文比较了两种球形蛋白质之间的电解质介导相互作用的表现形式。通过动态光散射（DLS）研究了含有不同类型钠盐的溶菌酶和牛血清白蛋白（BSA）溶液中的盐诱导蛋白质聚集。在第二个测量系列中，使用相同类型的离子来评估更稀的电解质对非聚集蛋白质分散体中蛋白质扩散率的影响。聚集和稳定扩散都表现出强烈的离子特异性，符合豪夫迈斯特系列：离液剂作为最强的凝聚剂，在稳定的蛋白质溶液中，导致最低的“蛋白质相互作用参数”，其评估方法为蛋白质扩散率与蛋白质浓度的斜率。在这种共同的定性趋势中，溶菌酶和 BSA 溶液表现出明显的差异，包括大多数测试溶液组成的相互作用参数的符号。尽管溶菌酶和 BSA 的性质不同，但在两种情况下，离子特异性相互作用参数与蛋白质的聚集趋势之间都存在很强的相关性，这由快速聚集所需的盐浓度来表示。通过对稳定蛋白质溶液进行快速简便的 DLS 测量，可获得相互作用参数，因此可用作离子特异性聚集趋势的预测因子。
