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Transformación de un complejo de hierro mononitrosil en un clúster [2Fe-2S] por un análogo de cisteína

Jessica Fitzpatrick¹, Harris Kalyvas, Milos R Filipovic

¹Department of Chemistry, Brown University , Providence, Rhode Island 02912, United States.

Journal of the American Chemical Society

|May 9, 2014

Resumen

Los investigadores demostraron un nuevo método para reparar los grupos de hierro-azufre [Fe-S] dañados por el óxido nítrico (NO). Este proceso convierte un complejo de hierro mononitrosil (MNIC) de nuevo en un clúster funcional [Fe-S] utilizando un análogo de cisteína.

Área de la Ciencia:

Química bioorgánica Química bioorgánica.
La bioquímica es la bioquímica.
Química de las metaloproteínas

Sus antecedentes:

El óxido nítrico (NO) modifica de manera reversible los grupos de hierro-azufre [Fe-S] en las proteínas reguladoras, actuando como un interruptor genético.
Si bien la modificación del clúster [Fe-S] inducida por NO está bien estudiada, el proceso inverso de reparación de estos clústers sigue siendo poco comprendido.

Objetivo del estudio:

Para investigar el mecanismo de reparación de los racimos [Fe-S] dañados por el óxido nítrico.
Para demostrar la conversión de un complejo de hierro mononitrosil (MNIC) de nuevo a un grupo [2Fe-2S] utilizando un análogo de cisteína.

Principales métodos:

Conversión de un MNIC específico, (PPN) [Fe(S(t) Bu) 3(NO) ] (1), a un clúster [2Fe-2S], (PPN) 2 [Fe2S2 ((SCH2CH2C ((O) OMe) [4] (2), mediante la adición de 3-mercaptometilpropionato (MMP).
Caracterización del grupo resultante utilizando métodos espectroscópicos, químicos, cristalográficos y analíticos.
Utilizando la espectrometría de masas y el etiquetado (34) S para rastrear el origen de los sulfuros puentes e identificar los mecanismos de captura de NO.

Principales resultados:

La adición de MMP solo a temperatura ambiente convirtió con éxito MNIC (1) en el grupo [2Fe-2S] (2).
Los datos espectroscópicos, químicos, cristalográficos y analíticos confirmaron la identidad del grupo [2Fe-2S] sintetizado.
La espectrometría de masas y el etiquetado (34) S indicaron que el MMP proporciona los sulfuros puentes para el racimo reparado.
El NO liberado fue efectivamente atrapado en un producto secundario del complejo de hierro dinitrosil, (PPN) [Fe ((SCH2CH2C ((O) OMe) 2 ((NO) 2) ] (4).

Conclusiones:

Los complejos de hierro de mononitrosilo (MNIC) son probablemente intermediarios en la reparación de los racimos [2Fe-2S] dañados por el NO.
La cisteína y sus análogos son moléculas viables que pueden desestabilizar los MNIC y facilitar la formación de grupos de [2Fe-S].

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