Match nmr tubes

NMR experiments were conducted at 298 K using a Bruker Avance III 700 MHz spectrometer equipped with a 5 mm inverse TCI cryoprobe and 3 mm diameter MATCH NMR tubes (Bruker). Water suppression was achieved by the excitation sculpting method using a 2 ms 180 degree selective Sinc1.1000 pulse at the H₂O frequency. Typical experimental parameters were as follows: number of transients 256, relaxation delay 2 s. Unless otherwise stated all samples were 400 μl final volume, consisting of 90% H₂O and 10% D₂O with the following concentrations in the reaction mixture: 5 mM 2HG, 50 μM (NH₄)₂Fe(SO₄)₂ and 10 mM L-ascorbate. The non-enzymatic reaction was started by addition of hydrogen peroxide with 5 mM as standard final concentration and then monitored for 2 h by ¹H NMR at 298 K.
The CPMG (Carr–Purcell–Meiboom–Gill) displacement experiments were conducted using the AV700 instrument and 3 mm MATCH NMR tubes32 (link). The PROJECT-CPMG sequence (90°_x–[τ–180°_y–τ–90°_y–τ–180°_y–τ]_n–acq) was applied as described by Aguilar et al.56 Typical experimental parameters were as follows: total echo time 48 ms (τ=2 ms, n=6), acquisition time 2.94 s, relaxation delay 2 s and number of transients 128. Water suppression was achieved by presaturation.