Solvation of the hydrophobic core. Snapshots from the UR3 simulation showing water and urea within 5.4 Å of residues 11, 16, 20, 49, and 57 (shown in space-filling representation). Water (green) is shown penetrating the top edge of the hydrophobic core at 1 ns. By 2 ns, urea (colored by atom) entered the hydrophobic core. The main-chain hydrogen bond of residue 57 and carbonyl oxygen atom of residue 11 is also shown at the top of the structures. The figure was made by using VMD (46) and rendered with RASTER3D (45).