Chae K S, Lenhoff A M
Department of Chemical Engineering, University of Delaware, Newark 19716, USA.
Biophys J. 1995 Mar;68(3):1120-7. doi: 10.1016/S0006-3495(95)80286-9.
A scheme is presented for computing the electrophoretic mobility of proteins in free solution, accounting for the details of the protein shape and charge distribution. The method of Teubner is implemented using a boundary integral formulation within which the velocity distribution, the equilibrium electrical potential around the molecule, and the potential distribution due to the applied field are solved for numerically using the boundary element method. Good agreement of the numerical result is obtained for spheres with the corresponding semi-analytical specialization of Henry's analysis. For protein systems, the method is applied to lysozyme and ribonuclease A. In both cases, the predicted mobility tensors are fairly isotropic, with the resulting scalar mobilities being significantly smaller than for spheres of equal volume and net charge. Comparisons with previously published experimental results for ribonuclease show agreement to be excellent in the presence of a net charge, but poorer at the point of zero charge. The approach may be useful for evaluating approximate methods for estimating protein electrophoretic mobilities and for using electrophoretic measurements to obtain insight into charge distributions on proteins.
本文提出了一种计算蛋白质在自由溶液中电泳迁移率的方案，该方案考虑了蛋白质形状和电荷分布的细节。采用边界积分公式实现了特布纳方法，在该公式中，利用边界元法对分子周围的速度分布、平衡电势以及外加电场引起的电势分布进行数值求解。对于球体，数值结果与亨利分析相应的半解析特解取得了良好的一致性。对于蛋白质系统，该方法应用于溶菌酶和核糖核酸酶A。在这两种情况下，预测的迁移率张量相当各向同性，所得标量迁移率明显小于等体积和净电荷的球体。与先前发表的核糖核酸酶实验结果的比较表明，在存在净电荷的情况下一致性非常好，但在零电荷点处一致性较差。该方法可能有助于评估估算蛋白质电泳迁移率的近似方法，以及利用电泳测量深入了解蛋白质上的电荷分布。
