Figure 6.

Modeling of the p21 substrate cleavage target into the putative gp13-Zn²⁺ containing active site. (a) Modeling of the p21 substrate target (carbon: yellow, oxygen: red, nitrogen: blue, hydrogen: white), containing the peptide bonds of Dpm-Ala-Dpm resulted in energy minimizations that favor orientation of the carbonyl group adjacent to the scissile bond (arrow) as the fourth Zn²⁺ ligand in gp13. All residues within 5 Å of the model fragment are shown (sticks) with six essential residues as rods. (b) The entire gp13 crystal structure is shown as a ribbon diagram for reference.