Fig. 5. Mutations at Asp⁶⁸⁷³ and Lys⁶⁸⁷⁴ reduce the efficiency of the nsp16 methyltransfer reaction.

(A and B) Plot of nsp16 methyl transfer activity across a concentration range for the indicated wild-type (WT) and mutant nsp16-nsp10 heterodimer complexes, plotted as the percentage of maximum (max) activity of the WT enzyme. Data are means and SD for biological triplicates conducted in two separate experiments (n = 6). Assays were conducted in the presence of MnCl₂ (A) or MgCl₂ (B). Black horizontal dashed line indicates 50% activity. (C) Calculated enzyme concentration for half-maximal activity (EC₅₀).