Figure 6

Catalytic mechanism of Plasmodium PNP. Schematic diagram showing the proposed generic Plasmodium PNP reaction mechanism, which is based on that initially proposed for Ec PNP [19]. Note that Asp 206 must be in its acidic form prior to protonation. The dotted lines indicate electrostatic interactions, dashed lines are hydrogen bonds and 'w' indicates water molecules. Panel (1) is the binding state, (2) is the pre-catalytic state, (3) is the intermediate state, and (4) is the pre-leaving state. See text for details of each step.