To monitor G6P oxidation by G6PDH, we hyperpolarized a G6P sample following the protocol described above, and recorded a series of C NMR spectra after its transfer into an NMR tube containing the enzyme. Experiments were performed with 150 units of enzyme activity (determined according to the supplier -Nzytech, 5000 U in 5 mL suspension). In our experiments, the initial concentration ratio in the NMR tube of NADP + over [U-13 C, U-2 H]-G6P was ∼ 6.7. The variation of [NADP + ] during the course of the experiment was therefore neglected, and was assumed approximately constant during the reaction. Experiments were acquired with proton and deuterium decoupling, and only the 1 J c-c couplings of C are resolved, leading to the hyperpolarized C spectrum obtained after dissolution shown in Figure . The 13 C resonance lines of the α and β anomer are located at 91.5 and 95.3 ppm, and the resonance peak at 174 ppm attests for the presence of the δ-6PGL carbonyl C . The oxidation reaction was thus monitored through the respective decay and buildups curves of the anomeric and carbonyl peak intensities. The typical reaction kinetic profiles, as depicted in Figure , were fitted to the model of Eq. 1 shown below. The kinetic curves of the three compounds were analyzed assuming first-order kinetics for all the reactions involved in the reaction pathway, which comprises mutarotation between the α and β anomers of G6P, and their oxidation by the G6PDH enzyme. As mentioned above, both processes take place on overlapping time scales on the order of a few tens of seconds. The enzyme reaction requires NADP + as a cofactor, which was added in large excess with respect to G6P (∼ 6.7 fold) to the solution so that oxidation was considered a pseudo-first order kinetics. Moreover, the kinetic model of the reaction pathway was further simplified by assuming that the isomerisation of the reaction product, δ-PGL, into γ-PGL, and the hydrolysis of both into 6-phosphogluconic acid (6PGA) 9;15 could be accounted for by a simple exponential leakage, i.e., a first order rate process. This reaction pathway is summarized in the scheme of Figure , and leads to the kinetic model for the magnetizations of G6P anomers and the lactone as given by Eqs. 1: