Electron tunneling pathways in respiratory complex I: The role of the internal water between the enzyme subunits

► Atomistic details of the electron tunneling pathways of respiratory complex I. ► Sensitivity of the pathways of N3 → N1b and N6b → N2 to the internal water molecules. ► Resulting hydrogen bonding networks provide new efficient pathways. ► Electron transfer rates are enhanced by two to three orders of magnitude.