Computational Analysis of Heat Capacity Effects in Protein-Ligand Binding

Area of Science:

• Biochemistry
• Computational Chemistry
• Structural Biology

Background:

• Heat capacity changes (ΔCp) in protein-ligand binding are critical for enzyme inhibitor design.
• A negative ΔCp indicates temperature-dependent binding enthalpy, relevant for optimizing interactions.
• Calorimetric experiments measure these effects, but computational prediction remains a key challenge.

Purpose of the Study:

• To assess the accuracy of computer simulations in predicting heat capacity changes during protein-ligand binding.
• To investigate the structural and energetic origins of negative ΔCp values observed in enzyme inhibitors.
• To evaluate molecular dynamics simulations for predicting ΔCp in drug design.

Main Methods:

• Utilized plain molecular dynamics (MD) simulations.
• Simulated both bound and free states of the enzyme and ligand.
• Examined a series of human thrombin inhibitors with known experimental ΔCp values.

Main Results:

• Computer simulations achieved accurate ΔCp estimates, within tenths of a kcal/mol/K of experimental values.
• The study successfully predicted ΔCp for human thrombin inhibitors binding with approximately -0.4 kcal/mol/K.
• Identified conformational equilibria of free ligands in solution as a major contributor to negative ΔCp.

Conclusions:

• Molecular dynamics simulations are a reliable tool for predicting heat capacity changes in protein-ligand interactions.
• Understanding the origins of ΔCp, such as ligand conformational entropy, aids in rational drug design.
• Accurate ΔCp prediction can guide the optimization of enzyme inhibitors and other therapeutics.