Comparison between the antigenicity of native and unfolded beta-lactoglobulin.

The antibody binding sites (B-cell epitopes) on beta-lactoglobulin (beta-LG) were surveyed by assaying the reactivity of the tryptic fragments of beta-LG to mouse anti-beta-LG antiserum with ELISA. Four peptide fragments (the residues 21Ser-40Arg, 41Val-60Lys, 102Tyr-124 Arg, and 149Leu-162Ile) bound the antibodies. We considered that B-cell epitopes of beta-LG were included in these fragments. Furthermore, these four tryptic fragments were also reactive with the antiserum to RCM beta-LG. Therefore, the unfolding of the beta-LG molecule is considered not to influence the localization of the antibody binding sites on beta-LG.