Dynamic disorder in receptor-ligand forced dissociation experiments

TL;DR

This paper introduces a dynamic disorder model using Gaussian stochastic rates to explain the counterintuitive increase in bond lifetimes under force, successfully matching experimental data on catch-slip bond transitions.

Contribution

The study proposes a novel dynamic disorder framework to explain catch-slip bond behavior, differing from previous models by emphasizing force-dependent rate fluctuations.

Findings

Model accurately fits experimental rupture data

Catch bonds linked to energy barrier and transition state correlations

Dynamic disorder explains force-dependent bond lifetime transitions

Abstract

Recently experiments showed that some biological noncovalent bonds increase their lifetimes when they are stretched by an external force, and their lifetimes will decrease when the force increases further. Several specific quantitative models have been proposed to explain the intriguing transitions from the "catch-bond" to the "slip-bond". Different from the previous efforts, in this work we propose that the dynamic disorder of the force-dependent dissociation rate can account for the counterintuitive behaviors of the bonds. A Gaussian stochastic rate model is used to quantitatively describe the transitions observed recently in the single bond P-selctin glycoprotein ligand 1(PSGL-1)$-$P-selectin force rupture experiment [Marshall, {\it et al.}, (2003) Nature {\bf 423}, 190-193]. Our model agrees well to the experimental data. We conclude that the catch bonds could arise from the stronger positive correlation between the height of the intrinsic energy barrier and the distance from the bound state to the barrier; classical pathway scenario or {\it a priori} catch bond assumption is not essential.