Application of a monoclonal antibody to a comparative study of alpha-lactalbumins from various species.

A monoclonal antibody to bovine alpha-lactalbumin was prepared and purified. The binding ability of alpha-lactalbumin from different species (cow, goat, giraffe, horse, pig, human, monkey, and guinea pig) was examined by a competitive radioimmunoassay. The order in strength of the binding affinity was cow goat, giraffe, horse, cynomolgus monkey and human, pig, and guinea pig. The order of evolutional divergence calculated from the amino acid composition was cow, goat, giraffe, horse, pig, guinea pig and human, and monkey. The orders in both cases were similar. Hence, it is suggested that immunological divergence as deduced by a monoclonal antibody is likely to be close to the evolutional divergence of alpha-lactalbumin.