Spinozzi Francesco, Gazzillo Domenico, Giacometti Achille, Mariani Paolo, Carsughi Flavio
Istituto di Scienze Fisiche, Università di Ancona, and INFM Unità di Ancona, I-60131 Ancona, Italy.
Biophys J. 2002 Apr;82(4):2165-75. doi: 10.1016/S0006-3495(02)75563-X.
In this work an improved methodology for studying interactions of proteins in solution by small-angle scattering is presented. Unlike the most common approach, where the protein-protein correlation functions g(ij)(r) are approximated by their zero-density limit (i.e., the Boltzmann factor), we propose a more accurate representation of g(ij)(r) that takes into account terms up to the first order in the density expansion of the mean-force potential. This improvement is expected to be particularly effective in the case of strong protein-protein interactions at intermediate concentrations. The method is applied to analyze small-angle x-ray scattering data obtained as a function of the ionic strength (from 7 to 507 mM) from acidic solutions of beta-lactoglobulin at the fixed concentration of 10 gl(-1). The results are compared with those obtained using the zero-density approximation and show significant improvement, particularly in the more demanding case of low ionic strength.
在这项工作中，提出了一种通过小角散射研究溶液中蛋白质相互作用的改进方法。与最常见的方法不同，在最常见的方法中，蛋白质-蛋白质相关函数g(ij)(r) 由其零密度极限（即玻尔兹曼因子）近似，我们提出了一种更准确的g(ij)(r) 表示，它考虑了平均力势密度展开中一阶以内的项。预计这种改进在中等浓度下强蛋白质-蛋白质相互作用的情况下特别有效。该方法用于分析在固定浓度10 g l(-1) 下，β-乳球蛋白酸性溶液中作为离子强度（从7到507 mM）函数获得的小角x射线散射数据。将结果与使用零密度近似获得的结果进行比较，结果显示有显著改进，特别是在离子强度较低这种要求更高的情况下。
