Epitope Mapping Using Phage-Displayed Peptide Libraries

Monoclonal antibodies (MAbs) play a key role in defining structural, functional, and regulatory aspects of complex protein-protein interactions (1 –4 ). The ability to identify the epitope recognized by an antibody and to understand how it relates to the primary or tertiary structure or the function of the protein has proven to be a difficult process. Epitope mapping experiments have shown that antigenic determinants fall into two major classes. Conformational or discontinuous epitopes consist of residues widely spaced in the primary sequence, yet brought in close proximity of one another by protein folding. These determinants are present on native protein, but are lost on denaturation or fragmentation. Linear or continuous epitopes contain at least four to six adjacent amino acid residues of the primary sequence and can be identified on denatured as well as native protein (5 –9 ).