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La unión de nitrógeno al cofactor FeMo de la nitrogenasa
Johannes Schimpl1, Helena M Petrilli, Peter E Blöchl
1Institute for Theoretical Physics, Clausthal University of Technology, D-38678 Clausthal-Zellerfeld, Germany.
Journal of the American Chemical Society
|December 18, 2003
Resumen
El mecanismo de fijación de nitrógeno de la enzima nitrogenasa implica la apertura de la jaula del cofactor FeMo al unirse el nitrógeno. Este proceso incluye transferencias de electrones y protones, rompiendo un puente de azufre y formando ligandos de nitrógeno axiales o puentes.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Química computacional es la química computacional.
- Enzimología Enzimología.
Sus antecedentes:
- La nitrogenasa es una enzima crucial para la fijación biológica del nitrógeno.
- Comprender los pasos iniciales de la fijación del nitrógeno es clave para mejorar los rendimientos agrícolas.
- El cofactor FeMo es el sitio activo responsable de la reducción del nitrógeno.
Objetivo del estudio:
- Para dilucidar las etapas iniciales de la fijación del nitrógeno por la nitrogenasa.
- Para caracterizar el mecanismo de unión del nitrógeno al cofactor FeMo.
- Para investigar los cambios estructurales y electrónicos durante la activación de la nitrogenasa.
Principales métodos:
- Se emplearon cálculos de la teoría funcional de la densidad (DFT).
- Se modeló el estado de reposo del cofactor FeMo.
- Se analizaron las vías de unión al nitrógeno y los intermediarios.
Principales resultados:
- La jaula Fe-Mo del cofactor FeMo se abre al unirse el dinitrógeno.
- La transferencia alterna de electrones y protones ocurre en el estado de reposo.
- La unión de dinitrógeno rompe un puente de azufre protonado.
- Se identificaron los modos de unión de nitrógeno axial y puente.
- La unión al sitio Fe es más favorable que la unión al sitio Mo para el dinitrógeno.
Conclusiones:
- El estudio revela pasos mecánicos clave en la fijación de nitrógeno catalizada por la nitrogenasa.
- Los hallazgos proporcionan información sobre el comportamiento dinámico del cofactor FeMo.
- El modelado computacional ayuda a comprender procesos enzimáticos complejos.
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