Protein identification by in-gel digestion and mass spectrometric analysis.

This protocol details a method for the identification of proteins that have been separated by gel electrophoresis. In-gel digestion of the protein bands with trypsin followed by quadrupole ion-trap or other triple quadrupole mass spectrometry techniques is described. The proteins can be identified by database searching of the mass fingerprint of the intact peptides and of the characteristic fragment masses produced by tandem mass spectrometry.