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Efecto del sulfuro de sodio en las deshidrogenases del monóxido de carbono que contiene Ni
1Department of Chemistry, Texas A&M University, College Station, 77843-3255, USA.
Journal of the American Chemical Society
|July 22, 2004
Resumen
Los iones sulfurados inhiben la actividad de la deshidrogenasa de monóxido de carbono (CODH) al unirse de forma reversible a la enzima.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Enzimología Enzimología.
- Química bioorgánica Química bioorgánica.
Sus antecedentes:
- La deshidrogenasa de monóxido de carbono (CODH) es crucial para el ciclo del carbono.
- La estructura del grupo C del sitio activo varía entre las enzimas CODH.
- Una diferencia clave es la presencia de un ion mu(2)-sulfuro en Carboxydothermus hydrogenoformans CODH, ausente en Rhodospirillum rubrum (CODH(Rr)) y Moorella thermoacetica (CODH(Mt)) CODH.
Objetivo del estudio:
- Investigar las diferencias estructurales y funcionales en los sitios activos de CODH.
- Explorar los efectos del sulfuro sobre la actividad de la CODH y las propiedades espectrales.
Principales métodos:
- Análisis de actividad enzimática. ensayos de actividad enzimática.
- Espectroscopia de resonancia paramagnética de electrones (EPR, por sus siglas en inglés).
- Análisis cinético para determinar las constantes de inhibición (K(I)).
Principales resultados:
- El sulfuro inhibió parcialmente la actividad de oxidación de CO en CODH (Rr) y CODH (Mt), causando un retraso en CODH (Rr).
- La unión de sulfuro a CODH ((Mt) en el estado C ((red1) alteró las señales EPR y fue reversible.
- Un modelo cinético propuso la unión de sulfuro reversible a C (red1), inhibiendo la catálisis y disuadiéndose tras la reducción.
Conclusiones:
- El sulfuro inhibe de manera reversible la actividad de la CODH al unirse al estado C ((red1).
- Los efectos inhibidores del sulfuro son análogos a los de otros aniones, lo que sugiere un modo de unión común.
- Esta unión puede implicar el puente de los átomos de Ni y Fe únicos en el cúmulo C.
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