How Complex Is the Concanavalin A-Carboxypeptidase Y Interaction?

Lectin-carbohydrate interactions can be exploited in ultrasensitive biochemical recognition or medical diagnosis. For this purpose, besides the high specificity of the interactions, an appropriate methodology for their quantitative and detailed characterization is demanded. In this work, we determine the unbinding properties of the concanavalin A-carboxypeptidase Y complex, which is important for characterization of glycoproteins on the surface of biological cells. To achieve the goal, we have developed a methodology based on dynamic force spectroscopy measurements and two advanced theoretical models of force-induced unbinding. Our final results allowed excluding both, rebinding processes and the multibarrier character of the interaction potential, as possible explanations of the concanavalin A-carboxypeptidase Y unbinding mechanisms. Such characteristics as the position and height of the activation barrier and the force-free dissociation rate were determined. We hope our paper contributes to a better understanding of the unbinding processes in receptor-ligand complexes.