Effect of the Cation Size on the Stability of RNA Structures

Abstract

The folding and subsequent stabilization of functional RNA structures depend strongly on the electrostatic screening of the negative charges on the phosphate group by alkali and alkaline earth metal ions. Such cations can either bind to structurally well-defined RNA sites or form a so-called ion cloud around RNA. However, it is difficult to directly observe these ions experimentally. The common view is that sodium ion is better in stabilizing RNA secondary structural elements than potassium ion that possess the same valance but a larger hydrodynamic radius.