Separation of closely related heptadecapeptides by micellar electrokinetic chromatography

Separations of five synthetic heptadecapeptides from the p-loop region of p21 Ras proteins, differing mostly in a single amino acid at the same position, were investigated. The studies were performed at low pHs in polyacryamide-coated capillaries, where the peptides were slightly positively charged. CZE, without surfactants, failed to separate all the peptides. Separations by MEKC employing an anionic surfactant sodium dodecyl sulfate (SDS), a neutral surfactant Tween 20 and a cationic surfactant cetyltrimethylammonium bromide (CTAB) provided results with varying degrees of success. Tween 20, slightly improved the separation while CTAB resulted in almost baseline separation of all the peptides. The effects of applying acetonitrile to MEKC were also examined. The separation results are analyzed with regard to the properties of the peptides and the surfactants. Implications of the results on peptide-micelle interactions and general aspects of peptide separation by MEKC are discussed. [References: 27]

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