Separation of acidic and basic proteins by CE with CTAB additive and its applications in peptide and protein...

In this paper, we report a very simple but efficient cationic micellar CE method for protein analysis in complex samples without any modification for the capillary wall. It was found that increased concentration (>or=2 mM) of CTAB additive in electrophoretic buffer can effectively suppress the wall adsorption of both acidic and basic proteins. The separation was improved with buffer pH decreasing from 6.0 to 3.0. By using a buffer containing 2 mM CTAB at pH 3.0, nine proteins with a wide range of pI values (4.7-11.0) were separated within 9 min with high efficiencies (>6 x 10(5) plates per meter) and good reproducibility (RSDs of migration time <0.8% for run-to-run assays) and recoveries (91.6-119.0%). This method was successfully applied to the analysis of complex biological samples, including plasma and red blood cells. Most importantly, we demonstrate the proteomic applications of the proposed method, including the analysis of tryptic digests of BSA and crude protein extracts from Escherichia coli cells. With simplicity, high efficiency, and good reproducibility, this method is promising for protein analysis in complex samples and may find its place in the future proteomic research.