Thermal stability of proteins in intermolecular complexes

Area of Science:

• Biochemistry
• Chemical Kinetics
• Protein Stability

Background:

• Protein thermal stability is crucial for biological function and biotechnological applications.
• Ligand binding is known to influence protein stability, but a unified model is lacking.
• Understanding these effects is key to protein engineering and drug development.

Purpose of the Study:

• To develop a general phenomenological model for estimating the impact of ligand complex formation on protein thermal stability.
• To jointly analyze reversible unfolding-refolding, association-dissociation of protein-ligand complexes, and irreversible protein degradation.
• To derive analytical expressions for thermodynamic and kinetic stabilization.

Main Methods:

• Development of a general phenomenological model.
• Joint analysis of reversible and irreversible processes.
• Application of approximations to derive analytical expressions.
• Investigation of protein-ligand complex formation and degradation kinetics.

Main Results:

• Analytical expressions for thermodynamic and kinetic stabilization were obtained.
• Two thermodynamic and four kinetic regimes of stabilization/destabilization were identified.
• Each thermodynamic regime can coexist with three distinct kinetic regimes.
• The influence of ligand binding depends on binding affinity to folded/unfolded states and degradation rates.

Conclusions:

• Ligand complex formation significantly impacts both thermodynamic and kinetic stability of proteins.
• The interplay between binding affinity and degradation rates dictates the overall stability.
• The model provides a framework for predicting and understanding protein stabilization by ligands.