Thermodynamics of globular proteins

Area of Science:

• Biophysics
• Thermodynamics
• Protein Chemistry

Background:

• Protein unfolding is crucial for understanding protein function and stability.
• Thermodynamic parameters provide insights into the forces governing protein structure.
• Quantifying unfolding in different environments, like the gas phase, aids in fundamental understanding.

Purpose of the Study:

• To analyze temperature-induced protein unfolding in aqueous solutions.
• To determine thermodynamic parameters of protein unfolding in the 'gas phase'.
• To investigate the relationship between protein size and unfolding characteristics.

Main Methods:

• Analysis of thermodynamic parameters of protein unfolding.
• Semi-empirical calculations of hydration parameters at 298 K.
• Determination of enthalpy, free energy, and entropy in the gas phase.

Main Results:

• Numerical values for enthalpy, free energy, and entropy of protein unfolding in the gas phase were obtained.
• Specific values for intramolecular bond energy (∆Hint), conformational free energy (∆Gconf), and entropy (∆Sconf) were found to be consistent for proteins between 7-25 kDa.
• Absolute free energy of native proteins (GNC) was calculated using intramolecular energy and a novel approach for conformational entropy.

Conclusions:

• The study provides a method to determine gas-phase thermodynamic parameters of protein unfolding.
• Conserved thermodynamic values for specific intramolecular interactions were identified in a defined protein size range.
• The findings contribute to a deeper understanding of protein stability and folding energetics.