Fig. 2: Characterization of the binding mode of C10 to SARS-CoV-2 NSP14.

a, b Dose-dependent inhibition curves of sinefungin against NSP14, with varying GpppG and SAM concentrations. SAM concentrations were increased while GpppG concentrations were fixed at 1.5 μM (a), or GpppG concentrations were increased while SAM concentrations were fixed at 1.5 μM (b). The obtained IC₅₀ values are presented as scatter plots. Data are presented as mean ± SD from three independent replicates. c, d Dose-dependent inhibition curves of C10 against NSP14 with varying concentrations of GpppG and SAM. In (c), SAM concentrations were increased while GpppG concentration was fixed at 1.5 μM. In (d), GpppG concentrations were increased while SAM concentrations were fixed at 1.5 μM. The IC₅₀ values obtained from (c) and (d) are presented as scatter plots. Data are shown as mean ± SD from three independent replicates. e Dose-dependent enhancement of the melting temperature (Tm) of SARS-CoV-2 NSP14 by compound C10 in the DSF assay. f, g In the presence of 200 μM GpppG (f), instead of 200 μM SAM (g), treatment with C10 caused an additional increase in the Tm of NSP14, exhibiting a synergistic effect between C10 and GpppG. h SPR binding data showing the interaction between C10 and immobilized NSP14, with data fitted to a 1:1 kinetic binding model. i, j SPR binding data indicating that the binding affinity of C10 with immobilized NSP14 is reduced in the presence of SAM (i) compared to GpppG (j), suggesting a SAM-competitive binding mode. Source data are provided as a Source Data file.