Molecular docking

Docking calculations were performed using Genetic Optimization for Ligand Docking (GOLD v5.2.2)⁵⁴. The crystal structure of the human POP (PDB ID: 3DDU)³⁰ with a resolution of 1.56 Å was downloaded from the protein data bank (www.rcsb.org). Before docking, all water molecules were removed, and hydrogen atoms were added to the protein. The POP active site was defined within a radius of 6 Å of the bound inhibitor. The Goldscore and Chemscore were used as the default scoring function and rescoring function, respectively. The Goldscore calculates the overall fitting of the ligand in the binding site by considering various factors, such as the H-bonding energy, van der Waals energy, ligand torsion strain, and metal interaction. The Chemscore measures the total free energy change that occurs on the ligand binding, and it considers the hydrogen bonding, hydrophobic-hydrophobic contact area, metal interaction and ligand flexibility. In total, 10 poses were produced for each ligand.