All systems were subjected to an initial 3 ps minimization at 1 K using a 0.1 fs stepsize, in order to remove bad contacts in the system after solvation. During this simulation time, a 200 kcal• mol -1 •Å -2 harmonic restraint was placed on all protein and substrate atoms in the simulation to restrain them to their crystallographic positions. The step size was then increased to 1 fs for the remained of the simulations (both equilibration and subsequent EVB simulations), and the temperature was gradually increased from 1 to 300 K while simultaneously dropping the harmonic restraints from 200 to 0.5 kcal•mol -1 •Å -2 on only the atoms in the EVB region (not taking into account the additional restraints on atoms outside the inner 85% of the water droplet). Once the system had reached 300 K, the system was subjected to a further 20 ns of equilibration. Each equilibration was performed ten times, with ten different sets of initial velocities, leading to 200 ns of equilibration time per system, and 5.4 μs of equilibration time over all systems considered in this work. The corresponding backbone root mean square deviations are shown in Figures S1 to