On the interaction between manganese cation (Mn2+) and the nucleic acid bases (T, U, C, A, G) in the gas phase

Abstract

AbstractThe coordination modes, the equilibrium geometrical structures, and the gas‐phase metal ion affinity for the Mn2+ metal cation interacting with uracil, thymine, cytosine, adenine, and guanine were determined considering different low energy tautomers for the free nucleic acid bases and by using the density functional theory. For uracil and thymine, the mono‐coordinated complexes coming from the metalation of the oxo tautomers are not minima, whereas the manganese ion forms stable compounds with high energy tautomers for which the bi‐coordination is possible. Also for cytosine, adenine, and guanine the bi‐coordination is the favored binding mode. Despite the cytosine and guanine free bases have different tautomers lying in a very narrow range of energy, the stabilities of the corresponding metalated complexes differ significantly. A reverse situation occurs for uracil and thymine for which we obtain manganese complexes of comparable stability, while the tautomeric forms of the isolated free bases are well separated in energy. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002