New Computational Approach for External Entropy in Protein-Protein Binding

Area of Science:

• Biochemistry and Molecular Biology
• Computational Chemistry
• Biophysics

Background:

• Noncovalent association of biomolecules is crucial for biological processes and drug development.
• Accurate estimation of binding thermodynamic parameters is essential for understanding molecular interactions.
• External entropy, arising from reduced positional and orientational degrees of freedom, poses a challenge in computational methods.

Purpose of the Study:

• To develop a novel statistical mechanical method for computing external entropy in biomolecular association.
• To address the underestimation of binding thermodynamics by accounting for coupled internal and external degrees of freedom.
• To provide a tractable method for estimating external entropy applicable to molecular dynamics simulations.

Main Methods:

• Extended an existing energetic approach for unimolecular processes to association processes.
• Incorporated intrinsic couplings between internal and external degrees of freedom of molecular complexes.
• Identified optimal external coordinates to minimize these couplings, leading to a tractable expression for external entropy.

Main Results:

• Demonstrated that internal-external degrees of freedom couplings are significant and cannot be neglected in general.
• Developed a method yielding the lowest upper bound for external entropy through a tractable expression.
• Successfully applied the method to the barnase-barstar complex, validating its applicability.

Conclusions:

• The novel method provides a more accurate estimation of external entropy in biomolecular association.
• This approach enhances the reliability of computational methods for predicting binding thermodynamic parameters.
• The technique is readily implementable with molecular dynamics simulations for various biological systems.