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Aniones de valencia en complejos de adenina y 9-metiladenina con ácido fórmico: estabilización por transferencia de
Kamil Mazurkiewicz1, Maciej Harańczyk, Maciej Gutowski
1Department of Chemistry, University of Gdańsk, Sobieskiego 18, 80-952 Gdańsk, Poland.
Journal of the American Chemical Society
|February 1, 2007
Resumen
Los aniones estables en fase gaseosa de los complejos adenina-ácido fórmico se forman a través de la unión de electrones, induciendo la transferencia de protones sin barreras. Esto sugiere que los aniones de purina pueden desempeñar un papel en el daño del ADN.
Área de la Ciencia:
- Química Física es la química física.
- Química cuántica es la química cuántica.
- Química biofísica y bioquímica.
Sus antecedentes:
- Los complejos aniónicos de nucleobases y sus derivados son cruciales para comprender el daño del ADN impulsado por electrones.
- Estudios previos se han centrado en los aniones pirimidina, con menos conocimientos sobre los aniones purina.
Objetivo del estudio:
- Para investigar la estructura electrónica y la estabilidad de los complejos aniónicos de ácido adenino-fórmico (AFA) y 9-metiladenina-ácido fórmico (MAFA).
- Explorar el mecanismo de adherencia de electrones en exceso y su efecto en la estructura molecular.
- Evaluar la relevancia biológica potencial de los aniones de purina en el daño del ADN.
Principales métodos:
- Experimental: Espectroscopia de fotoelectrones utilizando fotones de 2,540 eV.
- Computacional: Teoría de la función de densidad (B3LYP), teoría de la perturbación de Møller-Plesset (MP2) y métodos de racimo acoplado (CC).
- Conjuntos de base: 6-31++G** y doble zeta de valencia polarizada consistente en correlación aumentada (aug-cc-pVDZ).
Principales resultados:
- Se observaron aniones de valencia estables de AFA(-) y MAFA(-) experimentalmente con energías de unión de electrones de 1.5-1.4 eV.
- Los estudios computacionales confirmaron complejos neutros cíclicos estables enlazados con hidrógeno y calcularon estabilidades de aniones adiabáticos de 0,67 eV (AFA(-)) y 0,54 eV (MAFA(-)).
- El apego excesivo de electrones desencadena la transferencia de protones sin barreras del ácido fórmico a la adenina/9-metiladenina, formando radicales neutros solvados por formato.
Conclusiones:
- El estudio demuestra la formación de aniones estables basados en purinas en la fase gaseosa.
- La transferencia de protones sin barreras sobre la unión de electrones conduce a estructuras aniónicas únicas.
- Los hallazgos sugieren que los aniones de purina podrían ser significativos en el daño al ADN inducido por electrones de baja energía, similar a los aniones de pirimidina.
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