Harnessing Pressure Modulation for Exploring Ligand Binding Reactions in Cosolvent Solutions

Area of Science:

• Biochemistry
• Chemical Thermodynamics
• Molecular Biophysics

Background:

• Understanding ligand-protein interactions is crucial for drug discovery and molecular biology.
• Thermodynamic parameters, including volumetric properties, offer insights into binding mechanisms.
• Pressure-dependent studies complement temperature studies for a comprehensive analysis.

Purpose of the Study:

• To investigate the impact of pressure and dimethyl sulfoxide (DMSO) on the binding of proflavine to α-chymotrypsin.
• To elucidate the role of partial molar volume changes in ligand-protein complexation in the presence of a cosolvent.

Main Methods:

• Thermodynamic analysis of ligand-protein binding.
• Pressure-dependent binding studies.
• Spectroscopic methods to determine binding constants.

Main Results:

• Dimethyl sulfoxide (DMSO) acts as a competitive inhibitor, decreasing the binding constant of proflavine to α-chymotrypsin.
• In neat buffer, the binding reaction is largely pressure-insensitive.
• In the presence of DMSO, the partial molar volume of the complex is larger than the uncomplexed state, leading to a decrease in binding constant upon pressurization.

Conclusions:

• Partial molar volume changes provide valuable information about interaction mechanisms and hydration, especially with cosolvents.
• Pressure-dependent studies are essential for a complete understanding of ligand-protein binding thermodynamics.
• The presence of DMSO significantly alters the volumetric properties and binding affinity of proflavine to α-chymotrypsin.