The Role of Conformational Changes in Molecular Recognition

Area of Science:

• Biochemistry
• Computational Chemistry
• Molecular Biophysics

Background:

• Molecular recognition and binding free energy are central to biochemical processes.
• Conformational changes in molecules play a critical role in these interactions.
• Accurately quantifying the energetic contribution of these changes is essential.

Purpose of the Study:

• To derive a novel, exact mathematical equation for the binding free energy of receptor-ligand pairs.
• To define the energetic contribution of conformational changes using Kullback-Leibler (KL) divergence.
• To demonstrate that conformational changes unfavorably impact the association process.

Main Methods:

• Developed a new mathematical equation for binding free energy.
• Utilized Kullback-Leibler (KL) divergence to quantify conformational ensemble differences.
• Applied the method to ligand binding in T4 lysozyme's flexible cavity.

Main Results:

• Conformational changes' energetic contribution is precisely defined by KL divergence.
• These changes invariably contribute positively to the free energy change, hindering association.
• Enthalpy-entropy compensation can make conformational entropy a misleading metric.

Conclusions:

• KL divergence is the accurate measure for conformational contributions to binding free energy.
• Conformational changes are an energetic cost in molecular recognition.
• The derived equation provides a more rigorous framework for understanding binding thermodynamics.