Antigenicity of the 139-149 alpha(s1)-casein region in different species revealed by ELISA and immunoblotting using antipeptide antibodies

The antigenicity of the 139-149 alpha(S1)-casein region has been studied by using polyclonal antibodies raised against four different peptides. Two antisera, directed against the bovine 141-148 and 139-149 alpha(S1)-casein sequences, were found to be cow-specific in competitive ELISA tests. By immunoblotting, the recognized components corresponded to a set of minor bands distinct from the bovine alpha(S1)-casein, also detected by polyclonal antibodies against purified bovine alpha(S1)-casein fraction. The anti-(141-147) sequence stretch, common to bovine, water buffalo, caprine, and ovine alpha(S1)-casein, recognized the main alpha(S1)-casein components from the four milks, whereas the anti-(141-148) sequence stretch, present in water buffalo, caprine, and ovine alpha(S1)-casein, detected only minor alpha(S1)-casein components. Applications of these polyclonal antipeptide antibodies are suggested for the detection of bovine milk in mixture with milk from different species and for the evaluation of specific minor casein components.