Figure 5.

SARS-CoV-2 Mpro sequence variations at the active site. (a) The 20 most frequently occurring mutations (based on Figure 3) are shown by red sticks in the crystal structure of the enzyme (7RFS.pdb); the nirmatrelvir bound to the active site is also shown by sticks. (b) Enlarged view of the active site showing the inhibitor (gray) and the residues involved in nirmatrelvir binding. The residues are colored according to the number of the known variations in the given position.