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Dinámica de ligandos de monóxido de carbono y monóxido de nitrógeno en sistemas complejos sintéticos de hemo y
Heather R Lucas1, Gerald J Meyer, Kenneth D Karlin
1Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
Journal of the American Chemical Society
|September 10, 2009
Resumen
Los investigadores lograron una transferencia intermolecular sin precedentes de monóxido de nitrógeno (NO) y monóxido de carbono (CO) entre el hierro y el cobre. Este estudio revela diferentes afinidades de unión y tasas de transferencia, ofreciendo información sobre los mecanismos de las enzimas hemo-cobre.
Área de la Ciencia:
- Química bioorgánica Química bioorgánica.
- La fotoquímica es la fotoquímica.
- Mecanismos de las enzimas Mecanismos enzimáticos
Sus antecedentes:
- El monóxido de nitrógeno (NO) y el monóxido de carbono (CO) son moléculas y ligandos de señalización cruciales en los sistemas biológicos.
- Las proteínas hemo-cobre juegan un papel vital en la respiración celular y en las vías de señalización.
- Comprender los mecanismos de transferencia de ligandos es clave para dilucidar la función de las enzimas.
Objetivo del estudio:
- Para investigar la transferencia intermolecular de NO y CO entre los centros de hierro y cobre.
- Caracterizar la cinética y la termodinámica de estos procesos de transferencia de ligando.
- Para explorar las implicaciones para la función de la enzima hemo-cobre, como la citocromo c oxidasa.
Principales métodos:
- Se empleó la fotólisis de flash láser de absorción transitoria para estudiar la transferencia de ligandos.
- Se sintetizó un sistema modelo que comprende un complejo hemo ferroso de seis coordenadas y complejos de cobre (I).
- Se utilizaron diferentes entornos de coordinación de ligandos para el cobre (I) para sondear las preferencias de unión.
Principales resultados:
- Demostró la primera observación de transferencia intermolecular reversible de NO y CO entre el hierro y el cobre.
- Determinado que el cobre (I) exhibe una menor afinidad por el NO en comparación con el CO.
- Se observó una tasa de unión más alta para el NO en comparación con el CO en el centro hemo.
Conclusiones:
- El estudio establece un nuevo mecanismo para la transferencia de NO y CO entre las metaloproteínas.
- Los hallazgos sugieren que las afinidades diferenciales de ligandos y las tasas de transferencia son críticas para la función biológica.
- La cinética de unión hemo-NO observada es consistente con los mecanismos de la citocromo c oxidasa.
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