Investigating a link between all-atom model simulation and the Ising-based theory on the helix-coil transition: Equilibrium statistical mechanics

A study was carried out to examine the link between the two extreme models: the all-atom model and the Ising-based (Zimm-Bragg) model. By making comparisons between the molecular dynamic (MD) simulation results and the Z-B theoretical values with the aid of nonlinear fitting, it was shown that the Z-B theory is capable of reproducing the MD results at least qualitatively. The calculated chi-square landscapes in some cases, however, indicated that the obtained best-fit parameters were not robust and were sensitive to the data errors. On the other hand, some quantitative disagreements between the MD result and the Z-B theory were pointed out.