How Ligand Binding Affects the Dynamical Transition Temperature in Proteins.

Area of Science:

• Biophysics
• Protein dynamics
• Thermodynamics

Background:

• Protein function is linked to the protein glass transition temperature.
• Protein-water interactions are thought to influence this transition.
• The effect of ligand binding on this transition is not well understood at a molecular level.

Purpose of the Study:

• To investigate how ligand binding influences the protein glass transition temperature.
• To explore the molecular mechanisms behind ligand-induced stabilization.

Main Methods:

• Molecular dynamics (MD) simulations of the ϵ subunit from Bacillus PS3.
• Simulations conducted in both ATP-free and ligand-bound states.
• Temperature range from 20 to 300 K.
• Measurement of protein mean square displacement (MSD) to quantify dynamics.

Main Results:

• The protein glass transition temperature was largely unaffected by ligand association.
• Mean square displacement (MSD) increased more rapidly in the ATP-free state above the transition temperature.
• Ligand binding appears to stabilize protein domains with increasing temperature.

Conclusions:

• Ligand binding can stabilize protein domains by shielding the binding site from solvent.
• This shielding effect contributes to temperature-dependent protein stability.