Proton Transfers Induced by Lead(II) in a Uracil Nucleobase: A Study Based on Quantum Chemistry Calculations
| Autor: | Marie-Pierre Gaigeot, Thierry Cartailler, Jeanine Tortajada, Gutlé C, Jean-Yves Salpin |
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| Přispěvatelé: | Laboratoire Analyse et Modélisation pour la Biologie et l'Environnement (LAMBE), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université d'Évry-Val-d'Essonne (UEVE)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS) |
| Rok vydání: | 2006 |
| Předmět: |
Models
Molecular Spectrometry Mass Electrospray Ionization Pyrimidine Cations Divalent Stereochemistry 010402 general chemistry 01 natural sciences Nucleobase chemistry.chemical_compound Deprotonation Tandem Mass Spectrometry Computational chemistry 0103 physical sciences Organometallic Compounds Physical and Theoretical Chemistry Uracil Exergonic reaction 010304 chemical physics 0104 chemical sciences Thymine Lead chemistry Intramolecular force Quantum Theory Thermodynamics Density functional theory [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph] Protons |
| Zdroj: | Journal of Physical Chemistry A Journal of Physical Chemistry A, American Chemical Society, 2006, 110 (41), pp.11684-11694. ⟨10.1021/jp0621528⟩ Journal of Physical Chemistry A, 2006, 110 (41), pp.11684-11694. ⟨10.1021/jp0621528⟩ |
| ISSN: | 1520-5215 1089-5639 |
| DOI: | 10.1021/jp0621528 |
| Popis: | International audience; 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. |
| Databáze: | OpenAIRE |
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