We tested the pathway of the histidine-catalyzed fuel consumption. By 31 P-NMR, we observed the conversion of MAP, the production of inorganic phosphate (Pi), and the emergence and decay 1-phospho-histidine (1-pH), 3-phospho-histidine (3-pH), and 1,3-bisphospho-histidine (1,3-bpH, Fig. and Fig. ). Thus, all possible phosphorylated histidine species were observed. Even more exciting was that all species were only transiently present at the expense of MAP, pointing to the dynamic phosphorylation of histidine at the expense of MAP. The concentration of 3-pHis reached the highest maximum concentration of all species, which peaked at around 9 hours. The others, 1-pHis and 1,3-bispHis, peaked earlier and at lower concentrations. After 60 hours, all 75 mM histidine was deactivated to its dephosphorylated state, and all MAP was converted into inorganic phosphate. Besides the dynamic phosphorylation of histidine, no notable side reactions were observed. The same phosphorylated species were observed when we used DAP as a fuel. However, some side products were found. We conclude that histidine is a catalyst for the hydrolysis of MAP and DAP and is dynamically phosphorylated.