Fig. 4

A Interaction between a best-docked complex of ethyl 5-oxo-2-pyrrolidinecarboxylate and SARS-CoV-2 main protease (Mpro; PDB ID: 6LU7) using Ligplot. Only one residue (Gln189, H-bond = 3.18 Å) of protein was involved in the hydrogen bond between the O-group of protein and the N-group of ligand (B) Interaction between the best-docked complex of ethyl 5-oxo-2-pyrrolidinecarboxylate and SARS-CoV-2 papain-like protease (PLpro; PDB ID: 6W9C) using Ligplot. Three H-bonds are involved in the docked complex: i) between N-group of amino acid residue and O-group of ligand with bond length 2.82 Å, ii) between O-group of amino acid residue and N-group of ligand with bond length 2.72 Å, and iii) between N-group of amino acid residue and O-group of ligand with bond length 3.12 Å. The red-brown color in the half-circle indicates the residue of proteins that are involved in hydrophobic interaction with ligands. Green dotted lines show the hydrogen bond and the value indicates their bond length. C and D represents 3-D interaction by Ball and Stick model of interacting amino acids residues of SARS-CoV-2 Mpro and PLpro with ethyl 5-oxo-2-pyrrolidinecarboxylate, respectively using BIOVIA Discovery Studio 2021