Catch Bonding in the Forced Dissociation of a Polymer Endpoint

TL;DR

This paper demonstrates that catch bonding, where force initially stabilizes bonds, is a generic phenomenon expected in nonlinear force scenarios, confirmed through theory and molecular dynamics simulations, especially in polymer-related systems.

Contribution

It identifies the conditions under which catch bonding occurs, showing its generic presence in polymer and protein bonds through theoretical analysis and simulations.

Findings

Catch bonding occurs in nonlinear force scenarios.

The phenomenon is predicted by Kramers and Mean First Passage Time theories.

MD simulations confirm the theoretical predictions.

Abstract

Applying a force to certain supramolecular bonds may initially stabilize them, manifested by a lower dissociation rate. We show that this behavior, known as catch bonding and by now broadly reported in numerous biophysics bonds, is generically expected when either or both the trapping potential and the force applied to the bond possess some degree of nonlinearity. We enumerate possible scenarios, and for each identify the possibility and, if applicable, the criterion for catch bonding to occur. The effect is robustly predicted by Kramers theory, Mean First Passage Time theory, and finally confirmed in direct MD simulation. Among the catch scenarios, one plays out essentially any time the force on the bond originates in a polymeric object, implying that some degree of catch bond behavior is to be expected in {\em any} protein-protein bond, as well as in more general settings relevant to polymer network mechanics or optical tweezer experiments.