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Measurement of the Potential Rates of Dissimilatory Nitrate Reduction to Ammonium Based on 14NH4+/15NH4+ Analyses via Sequential Conversion to N2O
Published on: October 7, 2020
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Definición de los Intermedios de la Proteína Nitrogenasa MoFe durante la Reducción bajo la Entrega Fotoquímica de
Bryant Chica1, Jesse Ruzicka2, Hayden Kallas3
1Biosciences Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States.
Journal of the American Chemical Society
|August 14, 2020
Resumen
Los puntos cuánticos de semiconductores entregan electrones fotoexcitados a la proteína nitrogenasa MoFe, lo que permite la producción de amoníaco. Este estudio identifica un intermediario reducido en dos electrones, revelando los pasos iniciales en la fotosíntesis artificial para la fijación de nitrógeno.
Área de la Ciencia:
- La bioquímica
- Ciencias de los materiales
- Fotocatálisis
Sus antecedentes:
- La proteína Nitrogenasa MoFe cataliza la producción de amoníaco utilizando la proteína Fe y el ATP.
- Los nanomateriales semiconductores pueden proporcionar electrones fotoexcitados para la nitrogenasa.
- La comprensión de la transferencia de electrones de los nanomateriales a la nitrogenasa es crucial para la fotosíntesis artificial.
Objetivo del estudio:
- Para investigar los intermediarios de reacción inicial del punto cuántico de CdS (QD): complejos proteicos de MoFe bajo activación fotoquímica.
- Para aclarar el mecanismo de la entrega de electrones fotoexcitados de los QD a la proteína MoFe.
- Para determinar el papel del grupo P en la transferencia de electrones.
Principales métodos:
- Espectroscopia de resonancia paramagnética de electrones (EPR) bajo bajo flujo de fotones.
- Activación fotoquímica de los complejos proteicos CdS QD:MoFe.
- Utilizando una variante de proteína MoFe (β-188Cys) para estudiar las vías de transferencia de electrones.
Principales resultados:
- Cambios redox inducidos por la iluminación en el sitio activo de la proteína MoFe (FeMo-co).
- Se observó una nueva señal EPR (g_eff = 4.5) asignada a un intermediario "E2" con dos electrones reducidos.
- El cúmulo P fue identificado como un sitio para la entrega de electrones fotoexcitados de CdS.
Conclusiones:
- La entrega directa de electrones fotoquímicos desde los CdS QD a la proteína MoFe inicia la fijación de nitrógeno.
- El estudio define los pasos iniciales y los intermedios en la reducción fotocatalítica de N2 apoyada por QD.
- El flujo de electrones y el cúmulo P juegan un papel clave en este sistema de fotosíntesis artificial.
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