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Intercambio de agua en las porfirinas de manganeso (III). Conocimientos mecánicos relevantes para el complejo
Dominik Lieb1, Achim Zahl, Tatyana E Shubina
1Friedrich-Alexander-Universität Erlangen-Nürnberg, Department Chemie und Pharmazie, Egerlandstr. 1, 91058 Erlangen, Germany.
Journal of the American Chemical Society
|May 14, 2010
Resumen
El intercambio de agua en las porfirinas de manganeso (III) es un proceso rápido, crucial para la comprensión de los sistemas biológicos como el fotosistema II y los mecanismos catalíticos para la dismutación del superóxido.
Área de la Ciencia:
- Química Inorgánica La Química Inorgánica es la química inorgánica.
- Química bioorgánica Química bioorgánica.
- Química Física es la química física.
Sus antecedentes:
- Los centros de manganeso (III) son vitales en los procesos biológicos, incluido el fotosistema II.
- La comprensión de la cinética de intercambio de agua en el Mn (III) es clave para dilucidar los mecanismos de reacción.
Objetivo del estudio:
- Determinar experimentalmente las constantes de velocidad y los parámetros de activación para el intercambio de agua en los complejos de porfirina Mn{III}.
- Para investigar la influencia de la carga de porfirina y el transligando en la dinámica de intercambio de agua.
Principales métodos:
- Se utilizaron técnicas de Resonancia Magnética Nuclear (RMN) dependientes de la temperatura y la presión (17) O.
- Cálculos de la Teoría Funcional de la Densidad Empleada (DFT) para apoyo teórico.
Principales resultados:
- Intercambio de agua establecido en las porfirinas de Mn (III) como un proceso rápido (k (ex) ≈ 10^7 s (-1)) con un mecanismo de I (d) a I.
- Se ha demostrado una dependencia mínima del tipo de cambio en la carga de la porfirina y el transligando, atribuida a los efectos de Jahn-Teller y la carga efectiva en el Mn.
- Los cálculos de DFT confirmaron ligeras variaciones en las longitudes de los enlaces Mn(III) -OH(2) e indicaron una carga efectiva más baja en el centro de Mn.
Conclusiones:
- El rápido intercambio de agua en las porfirinas Mn(III) proporciona información sobre la unión al sustrato en el fotosistema II.
- Los hallazgos apoyan el papel potencial de los centros de Mn en las vías catalíticas de la esfera interna para la dismutación del superóxido.
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