Force-clamp spectroscopy of reversible bond breakage

TL;DR

This paper analyzes the stochastic dynamics of reversible bond breakage and formation under constant force, using two-state models and analogies to photon emission to understand fluctuations and environmental effects.

Contribution

It introduces a framework combining two-state models and fluorescence analogies to study reversible bond dynamics under force, including environmental fluctuation effects.

Findings

Second moment of event distribution sensitive to exchange processes

Environmental fluctuations cause deviations from Markovian behavior

Analytical expressions for mean and variance of unbinding/rebinding events

Abstract

We consider reversible breaking of adhesion bonds or folding of proteins under the influence of a constant external force. We discuss the stochastic properties of the unbinding/rebinding events and analyze their mean number and their variance in the framework of simple two-state models. In the calculations, we exploit the analogy to single molecule fluorescence and particularly between unbinding/rebinding and photon emission events. Environmental fluctuation models are used to describe deviations from Markovian behavior. The second moment of the event-number distribution is found to be very sensitive to possible exchange processes and can thus be used to identify temporal fluctuations of the transition rates.