Extent of conformational change measured by DEER spectroscopy. NaVAb structure showing the positions investigated by DEER (PDB ID 4EKW). Fit to the background subtracted DEER echo intensity is plotted against evolution time. The corresponding interspin distance distribution (right) for the NaVSp1-P (black) and NaVSp1 (red) for different spin-labeled positions. The two expected distances (Cβ–Cβ) from the adjacent and nonadjacent subunits in NaVAb crystal structure are shown in black dotted lines. The shorter distance is from the adjacent subunits and the longer from the diagonal subunits. The dotted gray lines are distance distributions from rotamer simulation for respective positions on PDB ID 4EKW (potentially slow-inactivated NaVAb conformation) using MMM. The arrows highlight the direction of change. Asterisk denotes distance peaks that may arise from intermolecular spin interactions between individual tetramers.
