Abstract
For some years, a major goal of immunochemistry has been to determine the molecular architecture of the antibody-combining site and its cognate surface on the antigen, the antigenic determinant or epitope, and to determine the molecular basis of specificity and affinity. In recent years, the crystal structures of several antigen-antibody complexes have been determined. In addition, recombinant DNA technology is beginning to play an increasingly important role in analysis of protein-protein interaction including the study of antigen structure and its interaction with antibody. The purpose of this review is to briefly present some of the major and common properties of the antigen-antibody interface as it is known today and to demonstrate, using a few selected studies, the efficacy of using site-directed mutagenesis to study the nature of the antigenic surface of protein molecules and its interaction with antibody.