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Un estudio voltamétrico de la transferencia de electrones interdominio dentro de la sulfito oxidasa
Sean J Elliott1, Anne E McElhaney, Changjian Feng
1Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, OX1 3QR England, UK.
Journal of the American Chemical Society
|September 26, 2002
Resumen
La transferencia de electrones de la sulfitooxidasa (SO) del hígado de pollo se rige por su dominio heme b y el sitio activo de molibdeno. El SO unido a electrodos muestra una catálisis más lenta, lo que indica cambios conformacionales limitados para una transferencia eficiente de electrones.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- La electroquímica es electroquímica.
- La cinética de las enzimas.
Sus antecedentes:
- La sulfitooxidasa (SO) es una enzima clave en el metabolismo del azufre, utilizando cofactores de hemo b y molibdeno.
- La comprensión de los mecanismos de transferencia de electrones de SO es crucial para el análisis de la vía metabólica.
Objetivo del estudio:
- Para investigar el comportamiento electroquímico de la sulfitooxidasa (SO) del hígado de pollo inmovilizada en las superficies de los electrodos.
- Aclarar el papel del dominio hemo b y el sitio activo del molibdeno en el transporte catalítico de electrones del SO.
Principales métodos:
- Se empleó voltametría de película proteica utilizando grafito pirolítico y electrodos de oro.
- Se analizaron las señales electroquímicas de SO en presencia y ausencia de sulfito.
Principales resultados:
- Se observó una señal electroquímica distinta para el dominio heme b a +90 mV (vs SHE).
- La unión de sulfito indujo una onda catalítica, lo que indica el control de la transferencia de electrones por el dominio heme b.
- Se observaron tasas de rotación más bajas (2-4 s-1) en comparación con la solución (100 s-1), lo que sugiere cambios de conformación restringidos en el SO. atado al electrodo.
Conclusiones:
- El transporte catalítico de electrones en el SO está dictado por la electroquímica del dominio heme b y la transferencia intramolecular de electrones al sitio del molibdeno.
- La inmovilización de los electrodos limita la flexibilidad conformacional del SO, lo que afecta a la eficiencia catalítica.
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