Proton transfer induced by Lead(II) in a Uracil nucleobase: a study based on quantum chemistry calculations - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Journal of Physical Chemistry A Année : 2006

Proton transfer induced by Lead(II) in a Uracil nucleobase: a study based on quantum chemistry calculations

Résumé

Within the context of metal biotoxicity, electrospray ionization mass spectrometry experiments (ESIMS) have recently been performed by us on the pyrimidine nucleobases (B) uracil and thymine complexed with lead(II) [Int. J. Mass. Spectrom.2005, 243, 279]. Among the ions detected, [Pb(B)−H]+ complexes, where the base has been deprotonated, have been identified as producing intense signals. In the same study, quantum calculations based on density functional theory (DFT) have assessed the complexation sites and energies of [Pb(B)−H]+ ions. The present DFT investigations aim at giving an understanding on the energetics and mechanisms associated with uracil's loss of a proton. We specifically assess and quantify the role of lead binding in this process. For that purpose, intra- and intermolecular proton transfers have been considered. We have found that uracil (U) 1,3-tautomerization can be exergonic when uracil is complexed with Pb2+, in opposition to the situation without lead. The corresponding intramolecular processes were nonetheless found to occur at geological time scales. In contrast, the addition of a second body to [Pb(U)]2+ complexes, namely OH- or H2O (as found in the initial water droplet of ESIMS experiments), gives exergonic and fast uracil 1,3-proton transfers. Finally, we have shown that intermolecular proton transfers in uracil−H2O, uracil−OH-, or uracil−uracil complexes are able to explain the experimentally detected [Pb(U)−H]+ ions.

Dates et versions

hal-00106819 , version 1 (16-10-2006)

Identifiants

Citer

Claudine Gutlé, Jean-Yves Salpin, Marie-Pierre Gaigeot, Thierry Cartailler, Jeanine Tortajada. Proton transfer induced by Lead(II) in a Uracil nucleobase: a study based on quantum chemistry calculations. Journal of Physical Chemistry A, 2006, 110 (41), pp.11684-11694. ⟨10.1021/jp0621528⟩. ⟨hal-00106819⟩

Collections

CEA CNRS UNIV-EVRY
54 Consultations
0 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More