A low-pressure/vacuum 5 mm NMR tube (Wilmad Glass) containing 500 μL of the precursor solution was held in an oil bath maintained at 80°C. Para-enriched hydrogen gas was bubbled through the solution at 7 bar for 1 minute. Following this, the solution was pneumatically shuttled through PTFE tubing (1.6 mm O.D., 0.5 mm I.D.) using helium gas at 7 bar for 7 s into a second 5 mm NMR tube. This tube contained a solution of 5 μL fumarase in 145 μL D2O, and was held in an 11.7 T magnet at 25°C. After shuttling, pulse sequences were applied, and the signal was acquired every 4 s.