Principles for Tuning Hydrophobic Ligand-Receptor Binding Kinetics

Area of Science:

• Computational chemistry
• Molecular dynamics simulations
• Biophysics

Background:

• Understanding ligand-receptor binding kinetics is crucial for drug discovery and catalysis.
• The role of solvent, particularly water, in modulating binding events is complex and not fully understood.
• Hydrophobic interactions play a significant role in molecular recognition processes.

Purpose of the Study:

• To investigate how solvent effects in tunable receptor pockets influence the rate of hydrophobic ligand-receptor association.
• To elucidate the relationship between receptor physicochemical properties, water dynamics, and binding kinetics.
• To provide insights for designing efficient host-guest binding systems.

Main Methods:

• Explicit-water molecular dynamics (MD) simulations were employed.
• A model system of a spherical ligand binding to a concave receptor pocket was used.
• Receptor geometry and dispersion attraction were systematically modified to alter water occupancy and fluctuations.

Main Results:

• Minor modifications to receptor pocket geometry (e.g., increased depth) significantly accelerated water-mediated association.
• Hydrophobicity, quantified by hydration occupancy and fluctuations, strongly correlated with binding times.
• A strong coupling between solvent fluctuations and ligand dynamics was observed, exhibiting non-equilibrium effects that slow binding kinetics.

Conclusions:

• Physicochemical properties of nonpolar binding sites can be tuned to control key-lock binding kinetics via water-mediated forces.
• Solvent fluctuations and ligand dynamics are intimately coupled, influencing binding rates.
• This study enhances the understanding of solvent's role in host-guest binding, with implications for catalysis and pharmaceuticals.