FIG 3.

Superimposition of the structures of HpDppA (green) and the closed (dipeptide-bound, orange) and open (free, thin black line) forms of PsDppA. The dipeptide ligand of PsDppA is shown as black balls. PDB IDs: 4QFN for the closed form of PsDppA; 4QFK for the open form of PsDppA.