Capillary Electrophoresis in Structural Characterization of Polypeptides

Abstract

Capillary zone electrophoresis is efficient in peptide analysis, allowing short separation times, high resolution and high sensitivity (cf. Karger et al., 1989). These features make the technique attractive also for preparative attempts in structural analyses, but the small volumes (nl) and the correspondingly small amounts (fmol) have long been considered a difficulty in preparative applications. However, recently we showed that capillary zone electrophoresis can be used to recover peptides for structural analysis (Bergman et al., 1991; Bergman and Jornvall, 1992; Bergman, 1992). Sufficient amounts for sequence analysis are collected in only a few preparative separations, while single runs yield enough material for sensitive amino acid analysis by the phenylthiocarbamyl (PTC) derivatization method (cf. Bergman et al., 1986). Preparative results with similar capillary electrophoresis systems have also been reported by others (Smith et al., 1992; Omori, 1992). In addition, a finding that sensitive detection of underivatized amino acids is possible by capillary zone electrophoresis, provides novel opportunities for direct analysis of results from digestions with exopeptidases (Bergman et al., 1991). Apart from rapid purity checks of preparations from reverse phase HPLC or conventional chromatography (Large, 1991; Agerberth et al., 1991), capillary zone electrophoresis can furthermore provide support for the identity of an isolated peptide through comigration experiments with synthetic replicas (Sillard et al., 1992).