Figure 4. A graphic view of the human PPA1 homodimerization interface. The two protomers are rendered differently in surface mode and cartoon mode respectively. The surface areas are colored according to amino acid hydrophobicity on the Kyte-Doolittle scale, from dodger blue for the most hydrophilic, to white, to orange red for the most hydrophobic. The side-chains for some of the key residues belonging to the protomer rendered in cartoon mode are shown in sticks. Hydrogen bonds are represented as yellow sticks. Structured water molecules are shown as spheres.