Figure 5. NCP-NCP interaction is defined by the valency of cation neutralizing NCP charge.

Snapshots of the 10NCP/K⁺ (A), 10NCP/Mg²⁺ (B), and 10NCP/Co³⁺ (C) systems. Inserts below (B) and (C) illustrate close NCP-NCP interactions with the formation of stacked NCP pairs in the 10NCP/Mg²⁺ system and a dense NCP aggregate in the 10NCP/Co³⁺ system with combination of different types NCP-NCP contacts with stacking being dominant (note two NCP stacks, green-yellow and pink-blue forming a column). In the inserts, mobile cations and DNA phosphate groups are omitted for clarity.