Stacking Interactions in Nucleobases

Abstract

Vertical stacking interactions are essential for stabilizing the DNA double helix. This study investigates the interactions among all four nucleobases—adenine, guanine, cytosine, and thymine—using ab-initio quantum mechanical calculations at the RI-MP2 level with the aug-cc-pVDZ basis set. Our findings reveal that intermolecular interaction energies within the modelled dimers are predominantly influenced by dispersion effects. However, these energies do not correlate directly with dispersion alone. Instead, a significant correlation is observed with the electrostatic component of the Hartree-Fock (HF) interaction energy, underscoring the complex interplay of forces that govern stacking interactions. Additionally, analyses of modified nucleobase systems demonstrate the additivity of effects from heteroatom groups, suggesting their independent operation. The study classifies the relative impacts of different groups of heteroatoms, providing insights into how substituent modifications affect the molecular stability and interaction dynamics of all nucleobases.