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Cobre ((I) y cobre ((II) complejos que poseen ligandos cruzados imidazol-fenol: estructuras y reactividad de
Kaliappan Kamaraj1, Eunsuk Kim, Benedikt Galliker
1Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
Journal of the American Chemical Society
|June 6, 2003
Resumen
Los investigadores sintetizaron nuevos complejos de cobre con ligandos cruzados de imidazol-fenol para imitar el sitio activo de la citocromo c oxidasa. Estos complejos arrojan luz sobre el mecanismo catalítico de reducción de dioxígeno que implica la transferencia de electrones y protones.
Área de la Ciencia:
- Química bioorgánica Química bioorgánica.
- Química biofísica y bioquímica.
- Coordinación Química de la Coordinación
Sus antecedentes:
- La citocromo c oxidasa es crucial para la respiración celular, catalizando la reducción de oxígeno.
- Su sitio activo presenta un núcleo de hemo a3-CuB heterobinuclear.
- Se propone que una porción única de histidina-tirosina reticulada sea vital para la catálisis.
Objetivo del estudio:
- Para sintetizar y caracterizar los complejos de cobre que modelan la porción de histidina-tirosina entrelazada.
- Investigar la reactividad de estos complejos con el dioxígeno.
- Para obtener información sobre el mecanismo de la reducción catalítica de dioxígeno.
Principales métodos:
- Síntesis de los ligandos de piridilaquilamina tetra y tridentado con enlaces cruzados imidazol-fenol/anisol.
- Caracterización de los complejos de cobre (I/II) mediante cristalografía de rayos X.
- Estudios espectroscópicos y cinéticos de la unión y reacción del dioxígeno con complejos de cobre.
Principales resultados:
- Los complejos de cobre con enlaces cruzados imidazol-fenol/anisol fueron sintetizados y caracterizados con éxito.
- Los complejos reaccionaron con el dioxígeno, formando especies peroxo transitorias y complejos diméricos estables de cobre (II) - fenolato.
- Se obtuvieron datos cinéticos y termodinámicos para la formación de estos complejos diméricos.
Conclusiones:
- Los complejos de cobre sintetizados sirven como modelos funcionales para la porción de histidina-tirosina reticulada en la citocromo c oxidasa.
- El estudio proporciona información valiosa sobre el papel de esta fracción en la transferencia de electrones y protones durante la reducción del oxígeno.
- Los hallazgos contribuyen a comprender los intrincados mecanismos de las metalloenzimas involucradas en la respiración.
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