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Las interacciones donante-aceptor de electrones con las purinas flanqueantes influyen en la eficiencia de la
Zhengzheng Pan1, Mahesh Hariharan, Joshua D Arkin
1Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, USA.
Journal of the American Chemical Society
|October 29, 2011
Resumen
El "efecto purina" influye significativamente en los rendimientos cuánticos de fotodimerización de timina (Φ(TT)) en el ADN. El potencial de oxidación y la posición de las purinas flanqueantes dictan la extensión de la formación de dímeros de timina.
Área de la Ciencia:
- La fotoquímica es la fotoquímica.
- Biología Molecular Biología Molecular
- La biofísica es la biofísica.
Sus antecedentes:
- La fotodimerización de la timina es una vía clave de daño del ADN.
- La influencia de las bases flanqueantes en la fotoquímica del ADN no se entiende completamente.
Objetivo del estudio:
- Para investigar el impacto de las purinas flanqueantes en los rendimientos cuánticos de fotodimerización de timina (Φ(TT)) en el ADN.
- Para dilucidar los mecanismos detrás del observado "efecto purina".
Principales métodos:
- Determinación experimental de Φ(TT) para varias estructuras de ADN de una sola hebra y horquilla.
- Simulaciones de dinámica molecular para analizar el apilamiento de bases e interacciones.
- Espectroscopia UV-Vis para estudiar las transiciones electrónicas.
Principales resultados:
- Φ(TT) se correlaciona fuertemente con el potencial de oxidación de las purinas flanqueantes (inosina > adenina > guanina > deazaguanina).
- La posición de la purina (5' frente a 3') afecta significativamente a Φ(TT), especialmente para las purinas con menores potenciales de oxidación.
- La dinámica molecular reveló distintos patrones de apilamiento π en las horquillas de pelo frente a los hilos individuales.
- Las características de absorción de rayos UV sugieren que la excitación del complejo donante-aceptante contribuye al apagado de la dimerización.
Conclusiones:
- El "efecto purino" en Φ (TT) surge de una combinación de la conformación del estado fundamental, las interacciones entre donante y receptor de electrones y la formación de exciplex en estado excitado.
- Las purinas flanqueantes juegan un papel crítico en la modulación de fotodamage del ADN a través de efectos electrónicos y estructurales.
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