Bond Elasticity Controls Molecular Recognition Specificity in Antibody−Antigen Binding

ABSTRACT: Force-spectroscopy experiments make it possible to characterize single ligand−receptor pairs. Here we measure the spectrum of bond strengths and flexibilities in antibody−antigen interactions using optical tweezers. We characterize the mechanical evolution of polyclonal antibodies generated under infection and the ability of a monoclonal antibody to cross-react against different antigens. Our results suggest that bond flexibility plays a major role in remodeling antibody−antigen bonds in order to improve recognition during the maturation of the humoral immune system