Pulling and umbrella sampling The input structure used for pulling simulations with OpenMM was taken after NPT equilibration run with GROMACS. All the simulations were performed in the NVT ensemble at 300 K using Langevin integrator with a friction coefficient of 1 ps -1 and step size of 0.002 ps. Coulomb interactions were computed using the PME method. Van der Waals interactions were modeled with the Lennard-Jones potential with a cutoff of 1.2 nm. Constraints were used for bonds to hydrogens.