Capillary Electrophoresis of Proteins and Peptides

Capillary electrophoresis (CE) is a high‐resolution technique for the separation of a wide variety of molecules of biological interest such as metabolites, drugs, amino acids, nucleic acids, and carbohydrates. This unit focuses on the use of CE to separate proteins and peptides. As detailed here, CE can also be used to determine the isoelectric point of a protein, either in purified form or in a mixture, by focusing the sample in a pH gradient that is generated within the capillary during electrophoresis. In addition, CE can be used as a micropreparative technique, with either multiple separations that are pooled or a single, larger‐scale separation, for the isolation of peptides from a protease digestion (in much the same way that RP‐HPLC is currently used). In most of these examples the same capillary column can be used for all the separations. Only changes in buffer composition, ionic strength, and the presence or absence of additives are required for each specific application.