Figure 6.

Electrostatic surface potential maps of the structural models of the DB_WT domain of EGR1 containing H382 in unprotonated (a) and protonated (b) forms in complex with the ZRE duplex. Note that in the unprotonated form, H382 is protonated only at Nε2 atom within the imidazole ring, while it is protonated at both Nε2 and Nδ1 atoms in the protonated form. The blue and red colors respectively denote the density of positive and negative charges, while the apolar and polar surfaces are indicated by white/gray color on the molecular surfaces. In the expanded views, the location of H382 is clearly marked on the molecular surfaces with the parenthesis indicating the overall charge on this residue under unprotonated (0) and protonated (+) forms. The ZRE duplex is displayed as a “stick” model and colored green for clarity.