ON THE THEORY OF PHASE TRANSITIONS IN POLYPEPTIDES

We suggest a theoretical method based on statistical mechanics for treating the α-helix ↔ random coil transition in polypeptides. This process is considered to be a first-order-like phase transition. The developed theory is free of model parameters and is based solely on fundamental physical principles. We apply the developed formalism to the description of thermodynamical properties of alanine polypeptides of different lengths. We analyze the essential thermodynamical properties of the system, such as heat capacity, phase transition temperature, and latent heat of the phase transition. Also, we obtain the same thermodynamical characteristics from molecular dynamics simulations and compare the results with those of statistical mechanics calculations. The comparison proves the validity of the statistical mechanics approach and establishes its accuracy.