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Los modos de enlace para la primera adición de electrones y protones acoplados a FeMoco de la nitrogenasa
Timothy Lovell1, Jian Li, David A Case
1The Scripps Research Institute, La Jolla California 92037, USA.
Journal of the American Chemical Society
|April 25, 2002
Resumen
Los investigadores modelaron el sitio activo de la nitrogenasa, encontrando un intermediario preferido de hidróxido de hierro. Este puede ser el primer paso para liberar dihidrógeno del cofactor hierro-molibdeno.
Área de la Ciencia:
- La bioquímica y la química computacional.
- Mecanismos de las enzimas.
- Investigación de la fijación del nitrógeno.
Sus antecedentes:
- La nitrogenasa es crucial para convertir el nitrógeno atmosférico en amoníaco.
- El cofactor hierro-molibdeno (FeMoco) es el centro catalítico de la nitrogenasa.
- Comprender el mecanismo de reacción de FeMoco es clave para mejorar la fijación de nitrógeno.
Objetivo del estudio:
- Para modelar el estado de un electrón reducido y protonado del sitio activo FeMoco.
- Para identificar el sitio de protonación más estable dentro del FeMoco.
- Para aclarar los pasos iniciales de la liberación de dihidrógeno.
Principales métodos:
- Utilizó una combinación de la teoría funcional de la densidad de simetría rota (DFT) y el enfoque electrostático.
- Examinó varios sitios potenciales de protonación dentro de los átomos Fe, Mo, S, N y O de FeMoco.
- Calculó la favorabilidad energética de diferentes estados de protonación.
Principales resultados:
- Identificó un nuevo protón hidrídico ubicado asimétricamente en la cavidad central formada por seis sitios de hierro.
- Este intermediario de hidruro de hierro es el estado computacionalmente más favorecido energéticamente.
- La formación de este intermedio se propone como un posible paso inicial en la liberación de dihidrógeno.
Conclusiones:
- El intermedio calculado de hidruro de hierro proporciona información sobre el mecanismo de FeMoco.
- Este hallazgo sugiere una vía para la liberación de dihidrógeno independiente de la unión de dinitrógeno.
- Otras investigaciones pueden explorar este intermedio bajo condiciones fisiológicas.
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