Generalized Born model with a simple, robust molecular volume correction.

Area of Science:

• Computational chemistry
• Molecular dynamics simulations
• Biophysics

Background:

• Generalized Born (GB) models offer efficient solvent electrostatics representation for molecular dynamics (MD).
• Fast pairwise GB models approximate molecular surfaces using van der Waals radii, which can reduce accuracy by allowing unrealistic solvent penetration.
• Existing models lack a free energy barrier for atom separation, deviating from explicit solvent behavior.

Purpose of the Study:

• To enhance the accuracy of pairwise generalized Born models.
• To introduce a correction term that better describes solvent-excluded volumes.
• To improve the agreement of MD simulations with explicit solvent results.

Main Methods:

• Developed a simple analytic correction term for pairwise GB models.
• Integrated the correction into existing GB models.
• Validated the corrected model using molecular dynamics simulations of proteins.

Main Results:

• The correction accurately describes the solvent-excluded volume between atom pairs.
• Introduced a physically realistic free energy barrier for non-bonded atom separation.
• Corrected models produced protein hydrogen bond lengths and conformational ensembles closer to explicit solvent results.

Conclusions:

• The analytic correction significantly improves the accuracy of pairwise GB models.
• The enhanced models maintain computational efficiency while providing a better approximation of reality.
• This work advances the application of implicit solvent models in biomolecular simulations.