Production and Preliminary Characterization of Monoclonal Antibodies against Cationic Peanut Peroxidase

Ten monoclonal antibodies (McAbs) have been produced against the cationic peroxidase from peanut suspension cell culture. Eight of these antibodies were found to be of the immunoglobulin (Ig)G(1) subclass and two were of IgA subclass. A combination of competitive enzyme-linked immunosorbent assay, Western blotting analysis, and direct antigen-binding assay revealed that the antibodies are directed against four different epitopes on the cationic peroxidase and the McAbs can be subdivided into four groups. Only group A inhibits peroxidase activity. Group B and D bind equally well to the native and the denatured form of cationic peroxidase, whereas the remaining McAbs react with more or less reduced affinity to the denatured antigen. Group C probably recognizes a conformation-dependent epitope. All the McAbs cross react weakly with the anionic peanut peroxidase, suggesting a structural nonidentity as well as some similarity between these two peroxidase isozymes. Cross reactivities of these McAbs with peroxidases of various plant species were also demonstrated.