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Los ARN y ADN ricos en guanina que se unen al hemo catalizan robustamente las reacciones de transferencia de oxígeno
Lester C-H Poon1, Stephen P Methot, William Morabi-Pazooki
1Department of Molecular Biology & Biochemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada.
Journal of the American Chemical Society
|January 27, 2011
Resumen
Los ácidos nucleicos ricos en guanina complejos con hemo catalizan las reacciones de oxidación, transfiriendo oxígeno del peróxido de hidrógeno a varios sustratos. Esta transferencia de oxígeno dependiente del hemo tiene implicaciones para la comprensión de la vida temprana, la enfermedad y el desarrollo de nuevas terapias.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Biología Molecular Biología Molecular
- La catálisis es la catálisis.
Sus antecedentes:
- Los ácidos nucleicos ricos en guanina, incluidos el ARN y el ADN, forman estructuras G-cuadruplexas.
- Estas estructuras G-cuadruplex se unen fuertemente con el Fe (III) hemo, formando complejos con potencial catalítico.
Objetivo del estudio:
- Para investigar la actividad catalítica de diversos complejos G-cuadruplex-hemo.
- Para determinar el mecanismo y la fuente de oxígeno en las reacciones de oxidación mediadas por hemo.
Principales métodos:
- Utilizó varios cuádruplexos G de ARN y ADN ricos en guanina complejos con Fe (III) heme.
- Empleado (18) Peróxido de hidrógeno marcado con O para rastrear la transferencia de oxígeno.
- Realizó estudios cinéticos, incluido el análisis de Hammett, sobre la oxidación del sustrato.
- Se utilizó el acoplamiento molecular para modelar la interacción del hemo con una estructura G-cuadruplex.
Principales resultados:
- Los complejos G-cuadruplex-hemo catalizan robustamente las oxidaciones de dos electrones del tioanisole, el indole y el estireno.
- El oxígeno transferido a los sustratos proviene de la fracción de ferril activado del hemo.
- El análisis cinético de la oxidación del tioanisole no pudo diferenciar entre la transferencia directa de oxígeno y los mecanismos de rebote de oxígeno.
- La oxidación del indole produjo varios productos, incluidos los tintes índigo.
- El modelado estructural sugirió un sitio activo relativamente abierto en estas ribozimas y desoxirribozimas.
Conclusiones:
- Los G-cuadruplexos ligados al hemo son catalizadores efectivos para las reacciones de transferencia de oxígeno.
- Esta capacidad catalítica tiene amplias implicaciones para el origen de la vida, el diseño de las enzimas y las aplicaciones médicas.
- Investigaciones adicionales sobre la catálisis dependiente de hemo en los ácidos nucleicos podrían tener un impacto en las terapias de enfermedades oxidativas celulares y cáncer.
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