Experiments were performed on a 6.7 T Bruker prototype polarizer operated at 1.2 K. The µwave power was set to 350 mW and irradiation was performed at 187.9 GHz, modulated with a saw-tooth function over a range of 100 MHz. Polarization of C nuclei was achieved using cross-polarization transfer from 1 H 17 every 4 minutes. Monitoring of the evolution of the signal was achieved by small-angle C read pulses (10 o ) until a maximum C polarization has been reached. Maximum polarization was typically reached after ∼ 6 CP steps (∼ one hour) under µ-wave irradiation. Dissolution was then performed with 4.5 mL of 0.1 M HEPES buffer at pH 7.4 and 0.5 mL of D 2 O, heated to 150°C and at 11 bar pressure, that was flushed onto the frozen, hyperpolarized, sample. The liquid was then transferred under a continuous flow of pressurized Helium gas into a 10 mm NMR tube sitting inside a 9.4 T wide-bore NMR spectrometer. The NMR tube contained 600 µL of a 0.1 M HEPES buffer at pH 7.4, 100 µL of D 2 O , 50 µmol of MgCl 2 , 134 µmol of NADP+, for a total volume of 1 mL (cofactor in excess to ensure complete substrate conversion by the end of the experiment), as well as 120 µL of a 1 M NaOH solution (to fix the pH at 7.4). In addition, 150 µL (1U/µL) of a solution of G6PDH (from E. coli, Sigma Aldrich) was added to the buffer in the NMR tube. In order to avoid spurious delays during transfer, the polarized solution was directly pushed to the NMR tube under Helium gas pressure (8 bars). Transfer was completed in 3 seconds, although the G6P typically reached the NMR tube from the first transient, recorded ∼ 1 s after dissolution. The typical volume of hyperpolarized solution reaching the NMR tube was around 3 mL. After mixing with the hyperpolarized sample, the final sample volume was ∼ 4 mL.