Thus, for both histidine and Ac-GHG-OH, the 3-pH-isomer was the most stable. Yet, Ac-G(3-pH)G-OH's deactivation was drastically slower than that of 3-phistidine (Figure ), which aligns with our expectations. The slow deactivation increased the overall reaction time to an impractical duration of hundreds of hours, thus, we tested whether the overall cycle could be accelerated by introducing catalysts for the dephosphorylation-we varied the pH and added pyridine to the reaction solutions. Specifically, we used pH 5.5, 6,5, and 7.5 with and without additional pyridine (5, 15, 25 mM). We monitored the concentration profiles in response to fuel (Fig. ) and calculated the half-life via the slope of the apparent first-order decay (without pyridine k-3 Table , with pyridine k'-3, Table ). At pH 5.5 without pyridine, the half-life of Ac-G(3-pH)G-OH was 40.8 ± 9.5 hours, which increased to 59.7 ± 6.4 hours at pH 6.5 and to 143 ± 15 hours at pH 7.5 (Figure ). These findings align with the known acid-lability of the P -N bond. The observed half-life and, thus, overall cycle lifetime were reduced when the pyridine concentration increased. For example, from 59.7 ± 6.4 hours without pyridine at pH 6.5 to 12.1 ± 3.1 hours with 25 mM pyridine (Fig. ). However, at these higher pyridine concentrations, the observed yield was low (Fig. ). Furthermore, the yield was too low at low pH (5.5) and high pyridine concentration to determine the apparent Ac-G(3-pH)G-OH half-life.