Theoretical study of the interaction pattern and the binding affinity between procaine and DNA bases

Abstract

The interacting patterns and mechanism of the binding affinity between the local anaesthetic procaine and four DNA bases (adenine, cytosine, guanine and thymine) in neutral form have been investigated in gas phase using the Austin Model l and density functional methods. The results show that the complexes are mainly stabilized by the H-bonding interactions. The bond critical point properties of the optimized complexes were analyzed by using the atoms in molecules theory with DFT method and the results show that the presence of the C−H···O or C−H···N hydrogen bonding. The natural bond orbital analysis was performed to quantitatively evaluate the hydrogen bonding interaction. The interacting energy shows that the binding of procaine with guanine is the most strong, whereas its binding to cytosine exhibits relatively weaker stability. The strength order of the relevant transferred charge between procaine and DNA base with natural population analysis are consist with the HOMO–LUMO gap results for each complex. And the order is accord with the relevant electrochemical experimental results.