Antigenic Reactivity of Chemically Modified β-Lactoglobulins with Antiserum to Native β-Lactoglobulin

Abstract

The effect of chemical modifications of lysyl residues of bovine β-lactoglobulin on the reactivity with antiserum to native β-lactoglobulin was studied, using preparations of these proteins in which about 30% of lysyl residues had been reductively methylated or succinylated and about 95% had been maleilated or acetylated. The antigenic reactivity was assayed by electroimmunodif-fusion, precipitin ring test and passive cutaneous anaphylaxis inhibition technique. The reductive methylation and succinylation had little effect on the antigenic reactivity with antiserum to native β-lactoglobulin but a significant decrease in the reactivity was observed on the maleilation and acetylation. The maleilated and acetylated β-lactoglobulins migrated much faster than native β lactoglobulin on polyacrylamide gel electrophoresis, and this fact indicates that the net charge of β-lactoglobulin molecules is evidently affected by these modifications.