The kinetic model allows us to predict through which pathways the fuel was converted into inorganic phosphate, which we demonstrate in a Sankey diagram (Fig. ). At pH 6.5 and with 5 mM pyridine, 17 percent of the MAP was used to phosphorylate histidine directly. Most of the MAP was used to phosphorylate pyridine, and only a small fraction was transferred to the histidine. The majority of the MAP is hydrolyzed directly or hydrolyzed by phosphorylating pyridine. We used these calculations to produce the plots in Figures and, which show the pathway through which MAP is hydrolyzed. Either it is hydrolyzed directly or through phosphorylating histidine (black and unwanted) or it is hydrolyzed through phosphorylating histidine (purple and wanted). At low pH values, the cycle was inefficient-only 1% of fuel was used to make the transient 1-pHis isomer and 5% to the 3-pHis isomer at pH 5.5 (Figure ).