Force-Induced Selective Dissociation of Noncovalent Antibody-Antigen Bonds

Specific noncovalent binding between antibody and antigen molecules is the basis for molecular recognition in biochemical processes. Quantitative investigation of the binding forces could lead to molecular specific analysis and potentially mechanical manipulation of these processes. Using our force-induced remnant magnetization spectroscopy, we revealed a well-defined binding force for the bonds between mouse immunoglobulin G and magnetically labeled a-mouse immunoglobulin G. The force was calibrated to be 120 +/- 15 pN. In comparison, the binding force was only 17 3 pN for physisorption and much higher than 120 pN for biotin-streptavidin bonds. A unique rebinding method was used to confirm the dissociation of the antibody-antigen bonds. A well-defined and molecule specific binding force opens a new avenue for distinguishing different noncovalent bonds in biochemical processes.