Segmental antigenic site

Figure 1. A schematic diagram showing the mode of folding of Mb and Its antigenic structure. The solid black portions represent segments which have been shown to comprise accurately the antigenic sites of the protein. The striped parts, each corresponding to one amino acid residue only, can be part of the antigenic sites with some antisera. The dotted portions represent parts of the molecule which have been shown exhaustively to reside outside antigenic sites (1).

Although assembled antigenic sites are more numerous, both sites are topographic in that they are composed of structures on the protein surface. However, an antibody exerts high-affinity binding to segmental sites only when those sites are in a preferred conformation. Therefore, all determinants must be conformation specific. 

Protein and DNA sequence analysis, particularly comprehensive including prediction of transmembrane helical segments, antigenic sites, and the like... 

The antigenic determinants of the native lysozyme molecule appear to include most, if not all, of the surface residues, as evidenced by numerous studies (reviewed critically by Benjamin et al., 1984). This point of view contrasts with that of Atassi and Lee (1978), who claimed a limited antigenicity, based on a study of surface-simulated peptides. The sites delineated by the latter workers do not include Arg-68 (Fainanu et al., 1974), the loop region in general, or any of several other segmental regions previously demonstrated to function in this capacity, such as residues 1—20 and 123-129 (see Benjamin et al., 1984). 

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