CAPILLARY ZONE ELECTROPHORESIS AND MICELLAR ELECTROKINETIC CHROMATOGRAPHY, WITH TAURODEOXYCHOLATE AS MICELLAR AGENT, OF PROTEIN-KINASE-A PEPTIDE-SUBSTRATES

The separation of protein kinase A peptide substrates with the general formula -X-Arg-Arg-Ala-Ser-Y-, where X and Y may be the same or diffe rent amino aicds, was studied by capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MEKC). Taurodeoxycholate ( TDC) was used as the micellar agent. CZE was effective in separating a peptide series differing in the number of amino acids, but not for a series with a difference in the terminating amino acid. For the latter series, MEKC generally gave a higher selectivity, but some of the pep tide pairs were more easily separated by CZE, demonstrating the comple mentary character of the two techniques. The efficiency of the MEKC sy stem was typically < 50% of that of CZE, but its higher selectivity ge nerally outbalanced the lower efficiency regarding resolution. The dis tribution of the peptides to the micelles was studied by determination of retention factors. Electrostatic and hydrophobic forces were found to be determining factors in the distribution; the most highly charge d basic peptides were most heavily distributed; and for peptides with the same charge those containing more hydrophobic amino acids were mor e strongly distributed. The contribution of some structural features t o the distribution degree was also determined.