The approach for epitope mapping is the application of immunoaffinity separation and matrix assisted laser desorption/ionization (MALDI) mass spectrometry (MS). The epitope of β2-microglobulin was identified with this approach. The antigen β2-microglobulin was coupled to a monoclonal antibody, which was covalently immobilized on a cyanogen bromide (CNBr)-activated Sepharose bead. Consecutive digestion of the antigen with endoproteinase Glu-C, trypsin, aminopeptidase M and carboxypeptidase Y resulted in affinity-bound peptides containing epitope. The bound peptides were identified by MALDI-TOF MS. The epitope recognized by the monoclonal antibody was identified to be the peptide fragment 61～67 with the sequence SFYLLYY. Synthesized peptide indicated the same result.

Key words: β2-microglobulin, epitope, immunoaffinity, mass spectrometry