Fig. 6: The reaction mechanism and comparison of Nsp15 and RNase A active sites.
From: Tipiracil binds to uridine site and inhibits Nsp15 endoribonuclease NendoU from SARS-CoV-2
A, B Schematic drawings of reaction mechanism of Nsp15. A Transphosphorylation reaction that generates 2′,3′-cyclic phosphodiester. B Hydrolysis reaction from transition state. Residues shown in red are for RNase A and in black for Nsp15. Arrows depict electron transfer. The active site of RNase A (C) is compared with that of Nsp15 in the complex with transition state analog uridine 2′,3′-vanadate (D), and with Tipiracil (E). The transition state of the phosphate is present in both reactions.
