Hamiltonian replica exchange MD (HREX-MD) simulations on two designed Kemp eliminase variants from the KE07 series (R1 and R4) were performed using GROMACS 2018.4 patched with PLUMED v2.5. We used the same protocol as described in the prior work, 70 with simulations performed using 6 replicas with λ values scaled between 1.0 and 0.667 were used for each system (giving an effective temperature range of 300 to 450 K). All two KE07 variants were simulated for 200 ns each, using their available crystal structures, as summarized in Table . PyContact calculations were performed on 10,000 equally spaced frames (0.02 ns timestep) obtained from the neutral replica of the HREX-MD simulations.