Figure 2.

Schematic depicting dependence of RNA folding and hydrolysis on divalent metal ion concentration. Under aqueous conditions, divalent metal ions (in particular Mg²⁺ and Mn²⁺) can enhance RNA folding by both diffuse binding and site‐specific binding (highlighted in blue). In diffuse binding, hydrated Mg²⁺ ions interact nonspecifically with the nucleic acid via long‐range electrostatic interactions. In site binding, dehydrated or partially dehydrated Mg²⁺ ions (highlighted in blue) interact specifically with anionic binding sites, which are formed by the RNA fold to act as coordinating ligands for the metal ion. At high M²⁺ concentrations, metal ion catalysis leads to increased RNA hydrolysis.