Influence of the solvent structure on the electrostatic interactions in proteins

Area of Science:

• Biophysics
• Computational Chemistry
• Physical Chemistry

Background:

• Accurate estimation of protein-solvent interactions is vital for understanding biophysical processes.
• The influence of dynamic solvent microstructure on electrostatic interactions at interfaces remains a complex challenge.

Purpose of the Study:

• To calculate the pairwise electrostatic interaction (PEI) energy at the protein-solvent interface.
• To evaluate the contribution of solvent orientational polarization to PEI energy, considering hydrogen bond correlations.
• To develop an analytical model for nonlocal electrostatics at interfaces.

Main Methods:

• Modeling the protein-solvent interface system.
• Applying the concept of nonlocal electrostatics for interfacial systems.
• Deriving an analytical expression for PEI energy using a distance-dependent dielectric function.
• Performing asymptotic and numerical analysis of the dielectric function.

Main Results:

• An analytical expression for PEI energy was derived, resembling Coulomb's law with an effective dielectric function.
• Analysis revealed dielectric heterogeneity at the protein-solvent interface.
• Dielectric function values for short-distance interactions near the interface were found to be smaller than in classical models.
• Considering dynamic solvent microstructure significantly increases PEI energy at the interface.

Conclusions:

• The dynamic microstructure of solvents plays a critical role in modulating electrostatic interactions at protein interfaces.
• Classical models assuming uniform dielectric media may underestimate electrostatic interactions at protein-solvent interfaces.
• This work provides a more refined understanding of electrostatic interactions in biological systems.