ANTIGENIC REACTIVE REGIONS OF S-CARBOXYMETHYLATED BETA-LACTOGLOBULIN

Rabbit antibody to reduced carboxymethylated bovine .beta.-lactoglobulin (SCM-.beta.-Lg) was prepared and characterized in order to study the antigenic property of bovine .beta.-lactoglobulin (.beta.-Lg) which is a potential cause of an allergy to cow''s milk. On immunodiffusion analysis, a clear, single precipitin arc was produced between SCM-.beta.-Lg and its antiserum, while a barley discernible line was observed between .beta.-Lg and anti SCM-.beta.-Lg antiserum. Analysis of the quantitative precipitation of SCM-.beta.-Lg with .beta.-Lg-absorbed antiserum to SCM-.beta.-Lg indicated that there were at least four antigenic sites on SCM-.beta.-Lg. In a quantitative precipitin inhibition test and a two-step inhibition test involving an enzyme-linked immunosorbent assay, anti SCM-.beta.-Lg antibody reacted with peptides 1.apprx.65, 25.apprx.61, 25.apprx.107, 41.apprx.107, 62.apprx.107, 108.apprx.145, 125.apprx.145 and 146.apprx.162 from .beta.-Lg, whereas peptides located in the N-terminal region, i.e., 1.apprx.7, 8.apprx.24 and 25.apprx.40, and peptide 108.apprx.124 showed little or no measurable affinity for antibody to SCM-.beta.-Lg. These results indicate that SCM-.beta.-Lg has at least four antigenic sites, which are associated with regions 41.apprx.61, 62.apprx.107, 125.apprx.145 and 146.apprx.162 in the primary structure of .beta.-Lg.