The molecular basis for the chemical denaturation of proteins by urea

Molecular dynamics simulations of the protein chymotrypsin inhibitor 2 in 8 M urea at 60 degrees C were undertaken to investigate the molecular basis of chemical denaturation. The protein unfolded rapidly under these conditions, but it retained its native structure in a control simulation in water at the same temperature. The overall process of unfolding in urea was similar to that observed in thermal denaturation simulations above the protein's T(m) of 75 degrees C. The first step in unfolding was expansion of the hydrophobic core. Then, the core was solvated by water and later by urea. The denatured structures in both urea and at high temperature contained residual native helical structure, whereas the…