Calculating RMSD to reference crystal structures. We calculated the root-meansquare deviation (RMSD) between each frame of our trajectories and the closed (PDB ID: 4w52), intermediate (PDB ID: 4w57) and open (PDB ID: 4w59) crystal structures using the rmsd function in MDTraj (v.1.9.9). We used this function to center each trajectory and calculate the distance between all atoms in the Fhelix for each frame of our different trajectories and the reference crystal structures.