COMPUTER-SIMULATION AND EXPERIMENTAL VALIDATION OF THE ELECTROPHORETIC BEHAVIOR OF PROTEINS .2. MODEL IMPROVEMENT AND APPLICATION TO ISOTACHOPHORESIS

Our model for the computer simulation of the electrophoretic behavior of proteins has been modified with regard to the contribution of the protein to ionic strength. The Debye-Huckel-Henry approach, which treats a protein like any other polyvalent ion (i.e. the contribution contains the square of the valence), was replaced by the Linderstrom-Lang approximation, which assumes that a z-valent ion behaves as a monovalent ion with z-fold concentration. This produces a considerable difference in predicted protein behavior because of the consideration of the impact of ionic strength on protein mobility. The predicted isotachophoretic behavior of several proteins is shown to compare much better with experimental data when the Linderstrom-Lang approach is employed. The influence of the input protein data on both qualitative and quantitative simulation data is discussed, and the first computer simulations of isotachophoretic protein fractionation are presented, using an isotachophoretic scheme which includes low molecular mass spacers. Good agreement between simulation and capillary isotachophoretic data is shown.