In a postulated mechanism, Glu98 activates a water molecule, which attacks the phosphorus atom on the 1-phosphate of fructose 1,6-bisphosphate (figure 8). Asp121 and the C2-hydroxyl group may assist the transfer of a proton to the bridging oxygen (8). The hydrolysis of a phosphate ester can proceed through an intermediate of metaphosphate (dissociative mechanism) or through a trigonal bipryamidal transition state (associative mechanism). Model systems in solution support the dissociative pathway, whereas most enzymologists favor an associative mechanism for enzyme-catalyzed reactions (7). It is difficult to specify a mechanism that would work for all F1,6-BPase activity in living organisms.  Figure 8. Mechanism for F 1,6-BPase catalysis. The enzyme activates a water molecule, which attacks the 1-Phosphate. The bridging oxygen becomes protonated and fructose 6-phosphate is produced along with a Pi molecule. California Institute of Technology.