CHARACTERIZATION OF MONOCLONAL-ANTIBODIES THAT RECOGNIZE THE SOYBEAN (KUNITZ) TRYPSIN-INHIBITOR - BINDING TO THE INHIBITOR INTERRUPTS THE FORMATION OF THE TRYPSIN-INHIBITOR COMPLEX

Three monoclonal antibodies (mAbs) have been raised against the soybea n (Kunitz) trypsin inhibitor (SBTI), and designated 5H-10, 6D-12, and 7B-11. Isotyping revealed that all three are IgG variants. Western blo tting analysis has shown that (i) each monoclonal antibody specificall y recognizes SBTI, but not the Bowman-Birk inhibitor (BBI) from soybea n, and (ii) mAbs 5H-10 and 6D-12 recognize a peptide of the correct mo lecular weight in seeds of two soybean cultivars that contain distinct allelic forms of the inhibitor (designated as Ti-a and Ti-b). However , binding studies using ELISA have shown that the affinity for purifie d SBTI differs between the clones. Further, mAb 6D-12 can interrupt th e inhibition of trypsin by SBTI such that the activity of the proteina se is restored, while the other two monoclonals have no apparent effec t. These results suggest that the epitope for mAb 6D-12 differs from m Abs 5H-10 and 7B-11, and as such this set of monoclonal antibodies can be of use in further characterising the trypsin:SBTI interaction.