Fig. 4.

Dry globule formation. (A) The radial distribution functions g(r) between the center of mass (COM) of the protein and the COM of urea and water in the first 1 ns and 19th ns (19–20 ns). It clearly shows that the concentration of urea increases much faster than water within the core of the protein (≈20 Å), indicating that urea might intrude into the protein ahead of water. (B) The time dependence of the percentage of the initial backbone–backbone hydrogen bonds formed by the residue pairs of hydrophobic–hydrophobic (black), hydrophilic–hydrophilic (red), and hydrophobic–hydrophilic (green), respectively.