Quantifying the Kinetic Residence Time as a Potential Complement to Affinity for the Aptamer Selection.

Aptamers have been widely developed for biotechnological and therapeutic applications in recent years. Increasing evidence shows that the quality of the aptamer is determined not only by the thermodynamic stability but also by the kinetic residence time when binding with its target. However, both experimental and computational selection methods of aptamers concentrate solely on the binding affinity optimization. Here, we propose a computational method for the quantification of the residence time by describing the kinetics on the underlying funneled binding energy landscape of aptamer-target complex as a diffusion process. The quantified residence time is examined to have the capacity to discriminate native aptamer-target complexes against non-native ones. It is found that the residence time is correlated with the binding affinity but with significant dispersion, suggesting that the residence time can be a potential complement in selecting the aptamer. On the basis of the results, a two-dimensional selection method with both the thermodynamic binding affinity and the residence time as kinetic specificity is suggested for diverse applications of aptamers. This alters conventional aptamer selection methods by considering the kinetic residence time in addition to the affinity.