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Published on: March 14, 2019
Kinetics of protein-protein association explained by Brownian dynamics computer simulation
1Department of Chemistry, Tennessee Technological University, Cookeville 38505.
Summary
Protein association rates, like antibody-antigen binding, are rapid due to a diffusive entrapment effect. This process allows proteins to reorient during collisions, explaining observed kinetics without needing special steering forces.
Area of Science:
- Biophysics
- Biochemistry
- Computational Biology
Background:
- Protein-protein interactions are crucial for biological processes.
- Observed association rates are much faster than simple geometric models predict.
- Previous theories proposed steering forces or lengthy collisions to explain rapid kinetics.
Purpose of the Study:
- To investigate the mechanism behind rapid protein-protein association rates.
- To determine if diffusion alone can account for observed bimolecular rate constants.
- To test the hypothesis of a diffusive entrapment effect.
Main Methods:
- Utilized Brownian dynamics simulations.
- Modeled neutral spherical proteins with specific docking criteria (2 Å tolerance).
- Calculated the bimolecular rate constant for protein association.
Main Results:
- Predicted a protein association rate of 2 x 10^6 M^-1.s^-1.
- This rate is 2000 times faster than simple geometric calculations.
- The simulated rate matches experimentally observed protein-protein association rates.
Conclusions:
- Diffusive entrapment, not external steering forces, explains rapid protein association.
- Water molecules facilitate rotational reorientation during collisions, enhancing association.
- Simple diffusion adequately explains the kinetics of protein-protein bond formation.
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