On the binding of Mg2+, Ca2+, Zn2+ and Cu+ metal cations to 2 ′ -deoxyguanosine: Changes on sugar puckering and strength of the NN-glycosidic bond

The binding of Mg2+, Ca2+, Zn2+ and Cu+ metal cations to 2′-deoxyguanosine has been analyzed, using the hybrid B3LYP, Density Functional Theory (DFT) method and 6–311++G(d,p)6–311++G(d,p) orbital basis sets. Coordination geometries, absolute metal ion affinities, and free energies for the most stable complexes formed by Mg2+, Ca2+, Zn2+ and Cu+ with the nucleoside, 2′-deoxyguanosine, have been determined. Furthermore, the influences of metal cationization on the strength of the N-glycosidic bond, torsion angles and angle of Pseudorotation (P) have been studied. With respect to the results, it has been found that metal binding significantly changes the values of the phase angle of Pseudorotation (P) in the sugar unit of these nucleosides. In all modified forms, the length of the C1′–N9 bond increases. The Mulliken population analysis on atomic charges has been carried out on the optimized geometries. Natural Bond Orbital (NBO) analysis was also performed to calculate the charge transfer and natural population analysis of the complexes. Quantum Theory of Atoms In Molecules (QTAIM) was also applied to determine the nature of interactions.