Structural parameterization of the binding enthalpy of small ligands

Area of Science:

• Computational Chemistry
• Drug Design
• Structural Biology

Background:

• Ligand and drug design aims to optimize binding affinity, determined by free energy changes (enthalpy and entropy).
• Binding enthalpy reflects ligand-target interaction strength, making its prediction from structural data crucial.
• Existing structure/enthalpy correlations from protein stability data show limitations for small pharmaceutical ligands.

Purpose of the Study:

• To develop an empirical parameterization for predicting binding enthalpy of small ligands using structural information.
• To identify key factors influencing binding enthalpy in ligand-target interactions.
• To establish a reliable method for estimating binding enthalpy in drug discovery.

Main Methods:

• Empirical parameterization of binding enthalpy based on structural features.
• Analysis of intrinsic enthalpy, conformational changes, and protonation events.
• Inclusion of buried water molecules in structure/enthalpy correlation calculations.

Main Results:

• Binding enthalpy correlates with changes in solvent accessible surface areas.
• Accurate prediction requires considering intrinsic enthalpy, conformational, and protonation events.
• Including buried water molecules (5-7 Å from ligand) significantly improves correlation accuracy.
• A model accounting for seven protein systems and 25 ligands achieved a standard error of +/-0.3 kcal/mol.

Conclusions:

• A novel empirical approach accurately predicts small ligand binding enthalpy using structural data.
• Buried water molecules play a critical role in determining binding enthalpy.
• This method offers a valuable tool for optimizing ligand and drug design.