Capillary electrophoresis of peptides and proteins with plug of Pluronic gel.

Electromigration capillary methods are promising techniques in proteomics and they are still under research. We used a partial filling approach, i.e. a combination of gel and non-gel separation mechanisms in a single dimension. We tried using an interesting gel, Pluronic F 127, which can be considered as a surfactant capable of self-association both with isotropic and anisotropic gels. The Pluronic was inserted inside the capillary as a plug at the start of the capillary, and it provided separation at the first time. Separation by this gel was achieved according to molecular weight and/or hydrophobicity. The applicability of this method was demonstrated in the separation of real samples-peptides arising from collagen after CNBr or collagenase cleavage and albumin after trypsin cleavage (peptide mapping). Some peptides and proteins were selectively retained by the Pluronic gel. These interactions with the gel did not depended on their molecular weight alone, but they probably depend on a combination of both principles. It was confirmed that capillary electrophoresis with Pluronic plug can give us another new separation option, complementary to free solution capillary electrophoresis. The CE method presented here, consisting of a partial filling approach with combine gel and non-gel separation mechanisms seemed to be a promising method for the separation of complex mixtures of peptides.