Figure 3.

Ubiquitin hydration dynamics map. All amide hydrogens within NOE distance of solvent are shown as spheres. Sites are color coded as follows: dark blue – bound hydration sites (NOE/ROE ≤ −0.47), cyan – relatively slow hydration (−0.47 > NOE/ROE < −0.3), yellow – relatively fast hydration (−0.3 ≤ NOE/ROE), green – fast hydration (solvent-exposed, no water cross peaks). The dark blue hydration class corresponds to sites where water within NOE distance (4.3 Å) of the amide hydrogen has a residence time on the order of the correlation time of the protein (~10 ns) or longer. Green sites are those within NOE distance of solvent, yet show no cross peaks to water. These represent the fastest sites of hydration dynamics. Clustering of hydration dynamic classes is evident. A cluster of greatly restricted hydration sites (dark blue and cyan) is seen in the C-terminal region (top panel), while the sites of fastest hydration dynamics group along the solvent-exposed ridge of the alpha helix (center panel). Clusters of intermediate hydration dynamics are also visible along the mixed beta sheet (cyan grouping) and near the 3₁₀ helix (yellow grouping). The differential localization of these hydration dynamic classes illustrates the relative hydration dynamics across the ubiquitin structure. Images were created using PyMOL³⁹.