An improved simple polarisable water model for use in biomolecular simulation

Area of Science:

• Computational chemistry
• Biomolecular modeling
• Physical chemistry

Background:

• Accurate biomolecular simulations require precise water models for solvation.
• Existing polarizable water models (COS/G2, COS/D) compatible with GROMOS force fields have limitations in dielectric permittivity and dynamics.
• Biomolecules exhibit electrostatic inhomogeneity, necessitating water models that capture polarization effects.

Purpose of the Study:

• To develop and evaluate a new polarizable water model, COS/D2, for improved biomolecular solvation.
• To address the shortcomings of previous COS/G2 and COS/D models.
• To create a computationally efficient yet accurate water model for biomolecular simulations.

Main Methods:

• Development of the COS/D2 model with four interaction sites: one Lennard-Jones site (oxygen) and three permanent charge sites (hydrogens and a massless off-atom site).
• The off-atom site functions as a charge-on-spring (COS) polarizable site with damped field dependence.
• Compatibility with GROMOS biomolecular force fields was maintained.

Main Results:

• The COS/D2 model demonstrates a more accurate dielectric permittivity compared to COS/G2.
• It exhibits improved dynamics compared to the COS/D model.
• The model effectively captures the polarization response crucial for inhomogeneous biomolecular systems.

Conclusions:

• The COS/D2 model offers a cost-effective and realistic solution for biomolecular solvation.
• It represents a significant improvement over previous COS models for biomolecular simulations.
• This model enhances the accuracy of simulating proteins and other electrostatically complex biomolecules.