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Transferencia de electrones de la proteína al ADN en la cromatina irradiada
P M Cullis1, G D Jones, M C Symons
1Department of Chemistry, University of Leicester, UK.
Nature
|December 24, 1987
Resumen
El daño del ADN por radiación se entiende mejor mediante el estudio de la transferencia de electrones en complejos ADN-proteína. Los centros de ganancia de electrones en el ADN aumentan cuando se complejan con histonas, lo que sugiere una nueva vía para el daño del ADN en los eucariotas.
Área de la Ciencia:
- La biofísica es la biofísica.
- Biología Molecular Biología Molecular
- Química de la radiación Química de la radiación
Sus antecedentes:
- El daño directo al ADN por irradiación implica centros de ganancia de electrones en la timina y centros de pérdida de electrones en la guanina.
- Estos centros radicales son precursores de las rupturas de cadenas de ADN, potencialmente relevantes para las vías de daño in vivo.
Objetivo del estudio:
- Para investigar el impacto de la complejación ADN-proteína en la formación de centros radicales inducidos por la radiación.
- Para determinar si la transferencia de electrones entre las histonas y el ADN influye en los rendimientos de daño del ADN.
Principales métodos:
- Se utilizó la espectroscopia de resonancia de espín de electrones (ESR) para detectar y cuantificar los centros radicales en complejos de ADN y ADN-proteína.
- Se realizaron estudios en sistemas de ADN congelado seco e hidratado, así como en ADN complejo con proteínas histónicas.
Principales resultados:
- La irradiación del ADN por sí sola produjo rendimientos iguales de centros de ganancia de electrones (aniones radicales de timina, T.-) y centros de pérdida de electrones (cationes radicales de guanina, G+.).
- En los complejos ADN-histona, la fácil transferencia de electrones de la histona al ADN aumentó significativamente el rendimiento de T.-.
- Los centros de pérdida de electrones ("agujeros") generados en la proteína quedaron atrapados y no aumentaron los rendimientos de G + en el ADN.
Conclusiones:
- La complejación ADN-proteína altera la formación de radicales inducida por la radiación, favoreciendo la ganancia de electrones en el ADN.
- La transferencia de electrones de las histonas al ADN es un factor importante en las vías de daño del ADN dentro de los núcleos eucariotas.
- Estos hallazgos proporcionan información sobre los mecanismos del daño del ADN in vivo.
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