The structure of conformational, discontinuous binding surfaces that associate with a binding molecule, preferably the epitopes of monoclonal antibodies (mAbs) may be discovered. The binding molecule is used to select specific peptides from a peptide library that, in turn, are used as a binding surface (epitope) defining database that is applied via a novel computer algorithm to analyze the crystalline-structure of the original binding surface (antigen). An antigenic epitope-mimetic that is recognized by its original mAb may be reconstituted based on the segments of the epitope identified in the prediction. The basic elements of the binding domain on gp120 that is recognized by broadly neutralizing antibody b12 are disclosed, as in their use in making vaccines for preventing or treating HIV.