Investigation of stability of adenine and its tautomers in RNA and DNA, and their interaction with Na+, K+, Mg2+, Ca2+ and Zn2+

Abstract

Tautomeric reactions of adenine base (A1 → An, n = 2–16) were investigated in the gas and aqueous phases which some cases were reported for the first time. All 25 tautomers and 33 transition states were obtained on their ground state potential energy surface, while four types such as N–H→N, N–H→C, C–H→N and C–H→C were hydrogen abstractions. Also, the interactions of important cations such Na+, K+, Mg2+, Ca2+ and Zn2+ with adenine tautomers were studied in the gas and aqueous phases. There were three types of interactions between (N1 and N10), (N7 and N10), and (N3 and N9) of tautomers and cations. The interaction energy of all complexes demonstrated the stability of complexes so that interaction tautomers with Mg2+ and Zn2+ were stronger than others. In addition, the tautomers stability and their complexes were compared with each other in gas and aqueous phases.