Figure 3

The active site of the Pv PNP. The top panel illustrates the dimer pair and their binding sites with the bound sulphate anions (from the crystal structure) and the inosine substrates (modelled into the Pv PNP structure based on superimposition of the Pf PNP-inosine structure, PDB:2BSX). The bottom schematic diagram shows possible key residues of the Pv PNP active site (numbered according to the system previously used for Pf PNP) with hydrogen bonds as dashed lines. Most residues are from the parent monomer, while those labelled 'b' are from the neighbouring subunit across the dimeric surface.