Figure 4: Close-Up View of the Tomato PME Active Site. (A) Structure of tomato PME in which residues involved in catalysis (violet), in stabilization of the catalytic intermediate (orange), and in substrate binding (blue) are shown in ball and stick representation. (B) Further close-up view representation of amino acid residues and a water molecule (blue ball) putatively involved in catalysis; H-bond pattern is highlighted.