Structural propensities and entropy effects in peptide helix-coil transitions

Area of Science:

• Biophysics
• Computational Biology
• Protein Science

Background:

• The helix-coil transition is fundamental to protein folding and function.
• Statistical mechanical models are essential for understanding peptide configurations.
• Accurate calculation of the partition function is crucial for these models.

Purpose of the Study:

• To develop a method for exact calculation of the peptide partition function.
• To incorporate degeneracy factors using hydrogen bond and helix propensity terms.
• To enable comparison of theoretical predictions with experimental data.

Main Methods:

• Developed a method to calculate the partition function for peptides of varying chain lengths.
• Utilized hydrogen bond and local helix propensity interaction terms.
• Incorporated a degeneracy factor for exact calculations.

Main Results:

• Calculated partition functions for engineered peptide chains.
• Compared theoretical predictions with experimental data (helicity, heat capacity, denaturation).
• Achieved good agreement between calculated and experimental curves when accounting for experimental sensitivity.

Conclusions:

• The developed method accurately models the helix-coil transition in peptides.
• Interaction energies were determined and compared with known biochemical values.
• Quantified the difference in configurations between random coil and helical states.