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Quantitative interpretation of FRET experiments via molecular simulation: force field and validation
Robert B Best1, Hagen Hofmann2, Daniel Nettels2
1Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland.
Biophysical Journal
|June 4, 2015
Summary
High-quality molecular simulations aid in interpreting single-molecule Förster resonance energy transfer (FRET) experiments. This study provides force-field parameters for AlexaFluor 488/594, validating simulations against experimental data for biomolecular dynamics.
Area of Science:
- Biophysics
- Computational Chemistry
- Molecular Dynamics
Background:
- Single-molecule Förster resonance energy transfer (FRET) is a powerful technique for studying biomolecular dynamics.
- Accurate interpretation of FRET experiments relies on high-quality molecular simulations and validated force fields.
- AlexaFluor 488 and 594 are commonly used FRET dyes, but their simulation parameters require refinement.
Purpose of the Study:
- To develop and validate molecular simulation force-field parameters for AlexaFluor 488 and 594 dyes.
- To assess the accuracy of molecular dynamics simulations in reproducing experimental FRET data.
- To investigate potential complications in FRET experiments, such as dye-helix association.
Main Methods:
- Microsecond molecular-dynamics simulations of AlexaFluor 488 and 594.
- Development of accurate force-field parameters, focusing on solute-water interactions.
- Comparison of simulation results with experimental data, including equilibrium constants, association/dissociation rates, and fluorescence anisotropy decays.
- Explicit calculation of FRET transfer efficiencies for polyproline systems.
Main Results:
- Validated force-field parameters for AlexaFluor 488/594 enable accurate molecular simulations.
- Simulations successfully reproduced experimental equilibrium constants, association/dissociation rates, and fluorescence anisotropy decays.
- Accurate simulation of solute-water interactions is crucial for predicting fluorophore mobility.
- Dye-polyproline helix association was found to be modest and transient under tested conditions.
- Calculated FRET efficiencies for polyproline agreed well with experimental measurements.
Conclusions:
- Molecular simulations, when employing high-quality force fields, are a valuable tool for interpreting single-molecule FRET experiments.
- The developed parameters and simulation methodology provide a reliable approach for studying biomolecular dynamics using FRET.
- This combined experimental and simulation approach enhances the quantitative analysis of complex biomolecular systems.
