Valence and Association Constant of Rat Macroglobulin Antibody

Fractions containing 19S and 7S antibody were obtained by gel filtration from specifically purified rat anti-DNP antibody and from whole immune serum. The valence and the association constants (K 0 ) of the antibodies in each fraction were determined employing the monovalent hapten DNP-e-aminocaproic acid. Ten binding sites per molecule were found in the 19S antibody. The sites were distributed into two populations in which K 0 differed more than 100-fold. Each population consisted of about 50% of the sites in both native and specifically purified 19S antibodies. The binding data with the 7S antibody indicated a valence of two and a single population of sites that showed some heterogeneity.