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Dynamic disorder in receptor-ligand forced dissociation experiments.
Fei Liu1, Zhong-can Ou-Yang, Mitsumasa Iwamoto
1Center for Advanced Study, Tsinghua University, Beijing 100084, China. liufei@tsinghua.edu.cn
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|February 21, 2006
Summary
Dynamic disorder explains "catch bonds," where biological bonds strengthen under force before weakening. This study proposes a Gaussian stochastic rate model to describe these counterintuitive transitions, aligning with experimental data.
Area of Science:
- Biophysics
- Molecular Mechanics
- Biochemistry
Background:
- Biological noncovalent bonds exhibit complex force-dependent behaviors, including increased lifetimes under stretching (catch bonds) followed by decreased lifetimes at higher forces (slip bonds).
- Existing quantitative models struggle to fully explain the transition from catch to slip bond behavior.
Purpose of the Study:
- To propose and validate a novel model explaining the counterintuitive catch bond phenomenon.
- To demonstrate that dynamic disorder in the force-dependent dissociation rate can account for catch-slip bond transitions.
Main Methods:
- Development of a Gaussian stochastic rate model to describe force-dependent dissociation rates.
- Quantitative analysis and comparison of the model's predictions with experimental data from single P-selectin glycoprotein ligand 1-P-selectin force rupture experiments.
Main Results:
- The proposed Gaussian stochastic rate model accurately reproduces the observed catch-slip bond transitions.
- The model suggests that dynamic disorder, specifically a positive correlation between energy barrier height and distance from the bound state, underlies catch bond behavior.
Conclusions:
- Dynamic disorder of the force-dependent dissociation rate is a sufficient explanation for catch bonds.
- Classical pathway scenarios or a priori assumptions of catch bonds are not essential for explaining these phenomena.