The van der Waals interaction between protein molecules in an electrolyte solution.

Area of Science:

• Biophysics
• Computational Chemistry
• Physical Chemistry

Background:

• Understanding protein-protein interactions is crucial in molecular biology and drug design.
• Accurate calculation of intermolecular forces, like van der Waals, is essential for predicting protein behavior in solution.
• Electrolyte solutions introduce complexities due to charge screening and dielectric effects.

Purpose of the Study:

• To present a general computational formulation for calculating van der Waals interactions between proteins in electrolyte solutions.
• To model proteins at a residue level using an inhomogeneous dielectric approach.
• To investigate the orientation-dependent anisotropy of these interactions.

Main Methods:

• Development of a general formulation based on the boundary element method.
• Solving the linearized Poisson-Boltzmann equation to account for electrolyte effects.
• Application of an inhomogeneous dielectric model for protein molecules at the residue level.

Main Results:

• The study provides a method to calculate van der Waals interactions between two protein molecules in an electrolyte.
• Results for bovine pancreatic trypsin inhibitor demonstrate significant anisotropy in interaction energies.
• The calculated anisotropy can reach values on the order of tens of kilojoule per mole (kBT) depending on relative orientation.

Conclusions:

• The proposed formulation offers a robust approach for studying protein-protein interactions in physiological solutions.
• The significant anisotropy highlights the importance of considering molecular orientation in predicting binding affinities.
• This work contributes to a better understanding of molecular recognition and self-assembly processes in biological systems.