Protein and Peptide Identification by Capillary Zone Electrophoresis Tandem Mass Spectrometry

A method for highly sensitive protein and peptide identification by capillary zone electrophoresis/electrospray ionization tandem mass spectrometry (CZE/ESI/MS/MS) was described. A mixture of peptides Met enkephalin and Leu enkephalin was analyzed, and their amino acid sequences were identified, respectively, using CZE/MS/MS. Peptide mapping for a tryptic digest of horse cytochrome c was performed by the same method. The results indicated that almost all peptides generated by tryptic digestion were identified, and their sequences were interpreted by their collision induced (CID) mass spectra. Applying the uninterpreted CID spectra of the protein digest to searching in sequence database by the SEQUEST program could identify proteins conveniently and rapidly. The samples consumed in the CZE/MS/MS experiments were at picomole level, so this method is quite suitable for quality control of recombinant proteins and trace amount protein identification in the proteome research.