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Reducción heterolítica de los hidroperoxidos de ácidos grasos por complejos citocromo c/cardiolipina: función
Natalia A Belikova1, Yulia Y Tyurina, Grigory Borisenko
1Center for Free Radical and Antioxidant Health and Department of Environmental and Occupational Health, University of Pittsburgh, 100 Technology Drive, Suite 350, Pittsburgh, Pennsylvania 15219-3130, USA.
Journal of the American Chemical Society
|July 25, 2009
Resumen
Las peroxidasas del citocromo c (cyt c) metabolizan eficientemente los hidroperoxidos de ácidos grasos libres (FFA-OOH), una reacción crucial para la muerte celular programada. Este proceso, a diferencia del metabolismo del peróxido de hidrógeno, implica un mecanismo de escisión heterolítico distinto.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- La función mitocondrial y la función mitocondrial.
- Caminos de la Muerte Celular
Sus antecedentes:
- El citocromo c (cyt c) facilita el transporte de electrones mitocondriales.
- Atado a la cardiolipina (CL), el cito c actúa como una peroxidasa, catalizando la oxidación de CL esencial para la muerte celular programada.
- El peróxido de hidrógeno (H(2) O(2)) fue el sustrato establecido para esta actividad de la peroxidasa.
Objetivo del estudio:
- Para investigar sustratos alternativos para la actividad de la citoperoxidasa.
- Para dilucidar el mecanismo del metabolismo del hidroperoxido de ácido graso libre (FFA-OOH) por el cit. c.
- Para identificar los residuos de aminoácidos clave involucrados en el procesamiento de FFA-OOH.
Principales métodos:
- La Resonancia Paramagnética de Electrones (EPR, por sus siglas en inglés) es una técnica de captura de espín.
- Cromatografía líquida y espectrometría de masas (LC-MS).
- Simulaciones por computadora de las interacciones proteína-ligando.
Principales resultados:
- Los complejos Cyt c/CL exhiben una actividad de peroxidasa significativamente mayor con FFA-OOH (aprox. 3 órdenes de magnitud) en comparación con H(2) O(2).
- Los FFA-OOH se escinden predominantemente a través de un mecanismo heterolítico, produciendo ácidos grasos hidroxi.
- H(2) O(2) y el hidroperoxido de tert-butilo (t-BuOOH) se someten a una escisión homolítica.
- Los residuos de aminoácidos Arg(38) e His(33) son críticos para la escisión heterolítica del FFA-OOH.
Conclusiones:
- La actividad de la citc peroxidasa no se limita a H(2) O(2) sino que utiliza de manera eficiente el FFA-OOH.
- El mecanismo del metabolismo de FFA-OOH por el cito c implica una escisión heterolítica, distinta de la escisión homolítica de H(2) O(2).
- La regulación del metabolismo de FFA-OOH por el cito c puede ser vital para eliminar los hidroperoxidos tóxicos y sintetizar los ácidos grasos hidroxi-bioactivos dentro de las mitocondrias.
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