FIGURE 2.

The accessible widths of minor and major grooves in the bending direction, as functions of bending angle β (over six basepairs). The shaded circles denote the boundary between accessible/inaccessible widths for Na⁺ and Mg²⁺ ions. Note that the minor groove is always inaccessible for hydrated Mg²⁺, while the major groove is always accessible for Na⁺ over the shown β-range.