Energy-Driven Undocking (EDU-HREM) in Solute Tempering Replica Exchange Simulations

Area of Science:

• Computational chemistry
• Molecular dynamics
• Biophysics

Background:

• Calculating absolute binding free energy is crucial for drug discovery.
• Atomistic simulations in explicit solvent are computationally intensive.
• Defining reaction coordinates for ligand-receptor interactions is challenging.

Purpose of the Study:

• To introduce a novel computational strategy for calculating absolute binding free energy.
• To bypass the need for defining reaction coordinates in protein-ligand binding.
• To enable efficient calculation of binding free energy using a single simulation.

Main Methods:

• Hamilton replica exchange method (HREM) with a solute tempering scheme.
• Defining the ligand and active site as 'solute' and the rest as 'solvent'.
• Energy Driven Undocking (EDU-HREM) technique to favor ligand extrusion.

Main Results:

• Successfully calculated absolute binding free energy for FK506-related ligands with FKBP12.
• Demonstrated encouraging results compared to known dissociation constants.
• Provided insights into the binding/inhibition mechanism of FKBP12.

Conclusions:

• EDU-HREM offers a simplified and efficient approach for absolute binding free energy calculations.
• The method is applicable to various protein-ligand systems.
• This technique advances computational drug discovery and mechanistic studies.