Optimal Dielectric Boundary for Binding Free Energy Estimates in the Implicit Solvent

Area of Science:

• Computational chemistry
• Molecular modeling

Background:

• Implicit solvent models are crucial for calculating binding free energies.
• Accuracy depends heavily on dielectric boundary parameters like atomic and water probe radii.

Purpose of the Study:

• To optimize atomic radii for accurate binding free energy calculations using implicit solvent models.
• To develop a new parameter set, OPT_BIND5D, for enhanced computational predictions.

Main Methods:

• A multidimensional optimization pipeline was employed to determine optimal atomic radii.
• The optimization target balanced binding and hydration free energies to prevent overfitting.
• The OPT_BIND5D set was validated on 20 independent host-guest systems.

Main Results:

• The OPT_BIND5D set achieved high accuracy for binding free energies (RMSE 2.03 kcal/mol, MAE 1.68 kcal/mol, R=0.79).
• Performance is comparable to fixed-charge explicit solvent models.
• Optimal implicit salt concentration matched experimental conditions for best results.

Conclusions:

• The OPT_BIND5D parameter set significantly enhances the accuracy of implicit solvent binding free energy predictions.
• This method offers a computationally efficient alternative to explicit solvent models.
• Careful parameterization and matching experimental conditions are key for reliable implicit solvent calculations.