Peptide mobility and peptide mapping in capillary zone electrophoresis. Experimental determination and theoretical simulation.

The electrophoretic mobilities of 58 peptides that varied in size from 2 to 39 amino acids and varied in charge from 0.65 to 7.82 are presented. The measurements were conducted at 22 degrees C using a 10% linear polyacrylamide-coated column and a 50 mM phosphate buffer at pH 2.5. Excellent separation of peptides and highly reliable peptide maps of protein digests are routinely obtained using these experimental conditions. The electrophoretic data were used to test existing theoretical models that correlate electrophoretic mobility with physical parameters. The results indicate that the Offord model that correlates electrophoretic mobility with the charge-to-size parameter q/M2/3 offers the best fit of our reliable experimental data. Furthermore, we also obtained the capillary zone electrophoretic profile of the endoproteinase Lys-C digests of a peptide sequencing standard, melittin, and horse myoglobin under the same experimental conditions as described above. The resulting peptide maps were compared with corresponding theoretical simulation.