Simulation and optimization of peptide separation by capillary electrophoresis.

The different mobility equations that have appeared in the literature for predicting peptide mobility were compared. A modified equation that relates the mobility of individual proteolytic species of a peptide to its composition has been obtained: mu = 1758 log(1 + 0.297q)/M0.411, where mu is the electrophoretic mobility in 10(-9) m2/s.V, q is the integral value of the charge of the species and M its molecular mass. Also, a rough estimation of the set of pKa values for a peptide was developed. The usefulness of this equation together with a computer program for predicting separations of compounds by capillary zone electrophoresis is demonstrated, employing real electropherograms of peptides from the literature or from experiments.