Figure 4.

Ligand environments. (a) Environment of K₃, the K⁺ ion linking the wide loops 1 and 3, coordinating T₅, T₁₆, and T₁₈, with the eighth coordination position made up by a water molecule, with the inset showing the consistency of the K–O distances (in Å); (b) binding cavity of Λ-(I) highlighting the van der Waals surface of the nucleic acid partially enveloping the complex; and (c) surface of the narrow loop and the narrow groove with the spine of water molecules linking the hydrated Ba²⁺ (green sphere) with the hydrated K⁺ ion K₄. The environment of the Ba²⁺ ion is shown in Figure S7.