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Puerta de conformación de la transferencia de electrones de la proteína Fe de la nitrogenasa a la proteína MoFe
Karamatullah Danyal1, Diana Mayweather, Dennis R Dean
1Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, USA.
Journal of the American Chemical Society
|May 1, 2010
Resumen
La transferencia de electrones de la proteína Fe de la nitrogenasa está limitada por cambios conformacionales, no por la viscosidad. La presión osmótica revela este mecanismo de apertura, con las moléculas de agua jugando un papel clave en el proceso.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Biología Estructural Biología estructural.
- La bioenergética es la bioenergética.
Sus antecedentes:
- La proteína Fe de la nitrogenasa (cluster [4Fe-4S]) transfiere electrones a la proteína MoFe.
- La transferencia de electrones (ET) está acoplada a la hidrólisis de ATP.
- Los cambios de conformación en el complejo de la nitrogenasa sugieren que ET.
Objetivo del estudio:
- Para investigar la "hipótesis de intersección" de la transferencia de electrones en la nitrogenasa.
- Comprender el papel de los cambios conformacionales en la transferencia intracompleja de electrones.
- Para aclarar la relación entre la transferencia de electrones y la hidrólisis de ATP.
Principales métodos:
- Se estudió la oxidación intracompleja de la proteína Fe ((rojo) por la proteína MoFe.
- Utilizó varios solutos para sondear el control conformacional.
- Presión osmótica medida y efectos de viscosidad.
- Efectos del isótopo cinético del disolvente evaluado. efectos del isótopo cinético del disolvente.
Principales resultados:
- El bloqueo de la transferencia de electrones se confirma por la respuesta a los cambios de presión osmótica.
- No menos de 80 moléculas de agua están involucradas en la reacción.
- Los cambios de viscosidad no afectaron la tasa de transferencia de electrones.
- La ausencia del efecto del isótopo cinético del disolvente sugiere que la hidrólisis de ATP no limita la velocidad para ET.
Conclusiones:
- Cambios de conformación, modulados por la presión osmótica y las interacciones del agua, transferencia de electrones de puerta en la nitrogenasa.
- La transferencia de electrones precede a la hidrólisis de ATP y la liberación de Pi, desacoplando estos eventos.
- El mecanismo de acoplamiento de la hidrólisis de ATP a la transferencia de electrones sigue siendo complejo.
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