Free energy distributions in proteins.

Area of Science:

• Thermodynamics
• Protein Biophysics
• Statistical Mechanics

Background:

• Proteins in solution exhibit diverse enthalpy states.
• The distribution of these states is crucial for understanding protein behavior.
• Experimental heat capacity data provides insights into these distributions.

Purpose of the Study:

• To formulate a free energy function for protein enthalpy states.
• To determine the most probable enthalpy values for proteins.
• To analyze the temperature dependence of protein thermodynamic behavior.

Main Methods:

• Utilizing the maximum-entropy method to approximate enthalpy state distributions.
• Calculating enthalpy distribution moments from experimental heat capacity temperature dependence.
• Formulating a free energy function based on the enthalpy probability distribution.

Main Results:

• The free energy function graphically indicates the most probable protein enthalpy values.
• Protein free energy functions exhibit behavior between two-state and single-minimum models.
• The relative stability of states changes with temperature.
• The minimum shifts to higher enthalpies as temperature increases.
• Temperature dependence can be represented by a central free energy distribution.

Conclusions:

• The developed free energy function accurately predicts protein thermodynamic behavior.
• This approach offers a comprehensive understanding of protein denaturation.
• The central free energy distribution encapsulates all thermodynamic properties over the denaturation range.