An improved method for measuring the stability of a three-state unfolding protein

In the current three-state protein unfolding model, the two transitions are considered to be independent and each transition is fitted to a two-state unfolding model. This three-state unfolding process is therefore composed of two sequential two-state unfolding processes. In this paper, a modified method is presented to determine the value of the unfolding free energy δG _total⁰(H₂O)] for the three-state unfolding equilibrium of proteins. This method is demonstrated on the apoCopC protein mutant, Y79W-W83F-Cu, which unfolds via a three-state process. The value of ΔG _total⁰(H₂O) calculated using the modified method was found to be more accurate in determining ΔG _total⁰(H₂O) than the previously reported method.