2) 100 ps of heating from 1 K to 298 K in NVT ensemble; 3) 300 ps of density equilibration in NPT ensemble; 4) 7 ns of production simulation in NVT. All MD simulations were performed using a 2 fs time step. Harmonic RMSD restraints were imposed on heavy atoms of the protein and the ligand during minimization and heating and were gradually removed during density equilibration; no restraints were used during production simulations. The first 2 ns of the MD production simulation were discarded, and the average structure was obtained from the last 5 ns of the simulation. A trajectory frame with minimum RMSD of ligand heavy atoms with respect to the average structure was selected as a representative structure and used as the initial protein-ligand complex structure for TI simulations. A total of 39 independent replicates were performed.