Protein folding thermodynamics: a new computational approach

Area of Science:

• Physical Chemistry
• Computational Biology
• Biophysics

Background:

• Protein folding free energy quantifies protein stability but is computationally challenging to determine.
• Traditional methods using equilibrium population ratios are impractical at physiological conditions due to low folding/unfolding transition rates.

Purpose of the Study:

• To develop a computational method for calculating protein folding free energy using independent simulations of folded and unfolded states.
• To accurately determine the folding free energy of the villin headpiece subdomain.

Main Methods:

• Utilized molecular dynamics simulations to generate extensive data for the protein villin headpiece subdomain.
• Calculated solvation free energy and analyzed probability distributions of effective energy in folded and unfolded states.
• Applied the central limit theorem to model effective energy distributions as Gaussian.

Main Results:

• Effective energy distributions for both folded and unfolded states were well-described by Gaussian distributions.
• The protein folding free energy was calculated using the mean and width of these distributions.
• The computed folding free energy (-2.5 kcal/mol) closely matched experimental values (-2.3 to -3.2 kcal/mol).

Conclusions:

• The developed computational approach provides an accurate and efficient method for determining protein folding free energy.
• This method overcomes limitations of traditional approaches, particularly at physiological conditions.
• The findings validate the use of effective energy distributions for predicting protein stability.