A crystal structure of PF-07321332 in complex with the main protease is
available. The resolution is 1.6 angstroms.
EDT
The detailed mechanism of action is that a covalent bond is formed between a cysteine residue of the enzyme and the inhibitor. Not all protease inhibitors work in the same way. A nitrile group on the inhibitor forms a reversible covalent bond with the enzyme.