MP2 study on the hydrogen-bonding interactions between 4-thiouracil and four RNA bases

The 4-thiouracil (s 4 U) is a sulphur-containing analog of uracil, a natural component of RNA. In this work, we present the interaction energies of complexes formation involving s 4 U bound to the four bases in RNA: adenine (A), uracil (U), guanine (G), and cytosine (C). Full geometry optimizations have been performed for the studied complexes by MP2 method. The interaction energies were corrected for the basis-set superposition error (BSSE), using the full Boys–Bernardi counterpoise correction scheme. Hydrogen bonding patterns of these base pairs were characterized using NBO analysis and AIM analysis. We find that the order of stability for the base pairs is s 4 U: G > s 4 U: A > s 4 U: U ~ s 4 U: C.