Radial distribution functions for Na+ ions within 12 Å of phosphate group oxygen atoms in junction bases A16, C17, A36, and C37 for (A) STX-HS, (B) STX-MS, (C) OPN-HS, and (D) OPN-MS, and for the phosphate oxygen atoms of (E) CBD-HS, and (F) CBD-MS. The solid lines refer to the O1P oxygen atoms, and the dashed lines to the O2P oxygen atoms. Data are taken from 80 ns of stable MD.