Fig. 4: αSyn enhances AK2 catalytic activity.

1D proton NMR-based AK2 activity assay in the presence and absence of WT αSyn, αSyn fibrils, or C-terminal truncated αSyn (ΔC-αSyn). a Schematic illustration of the principle of the method. A pH-adjusted starting solution of a 1:2 AMP/ATP mixture is treated with AK2 to initiate the reaction. A series of 1D proton NMR spectra as a pseudo-2D are recorded. The intensities of the H8 proton of adenine are extracted and plotted over time. From this, a time constant (τ) is fitted to compare the activity in the presence of different αSyn species. b Concentration-dependent time constant (τ) in the presence of varying concentrations of different αSyn species is given. Data are presented as mean ± SD. The experiment was performed with three αSyn concentrations and n = 3 independent replicates per αSyn concentration (independent addition of αSyn to AK2), except for 0.238 μM of αSyn monomer and 1.2 μM of αSyn fibrils, which were tested with n = 2 replicates. Asterisk indicates statistically significant difference between given condition and control in the absence of αSyn (p-value = 0.0146, two-tailed t-test). Supplementary Fig. 6 shows an orthogonal assay testing the activity of AK2 influenced by αSyn. c–g Light scattering aggregation assay of WT (c), ΔC (d), E46K (e), A53T (f), and A30P (g) αSyn at a concentration of 300 μM in PBS pH 7.4 in the absence or presence of varying concentrations of AK2. The experiment was performed in triplicate. Mean values and SD are shown. h SDS-PAGE of αSyn pellet obtained after incubation of αSyn (300 μM) in the absence or presence of AK2 at different concentrations (150 μM, 300 μM, and 600 μM). The molar ratios of AK2 to αSyn are given at the top of the gel. The experiment in (h) was repeated twice independently. Source data are provided as a Source Data file.