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Ajuste del sesgo catalítico de las hidrogenasas productoras de gas de hidrógeno

Jacob H Artz^1,2, Oleg A Zadvornyy¹, David W Mulder²

¹Institute of Biological Chemistry , Washington State University , Pullman , Washington 99164 , United States.

Journal of the American Chemical Society

|December 10, 2019

Resumen

Las interacciones de proteínas cerca del sitio activo de las [FeFe]-hidrogenasas de Clostridium pasteurianum controlan el sesgo catalítico. Este mecanismo explica cómo las enzimas aceleran selectivamente la oxidación del hidrógeno o la reducción de protones.

Área de la Ciencia:

La bioquímica
La biofísica
Enzimología

Sus antecedentes:

Las hidrogenasas catalizan la oxidación reversible del gas hidrógeno, crucial para el metabolismo energético.
La actividad enzimática y el sesgo catalítico varían significativamente entre las hidrogenasas.
El papel del entorno proteico en la modulación del sitio catalítico de las [FeFe]-hidrogenasas sigue sin estar claro.

Objetivo del estudio:

Investigar cómo las interacciones secundarias de proteínas influyen en el sesgo catalítico de las [FeFe]-hidrogenasas.
Elucidar el mecanismo por el cual el entorno proteico estabiliza los estados de oxidación específicos del grupo metálico del sitio activo.

Principales métodos:

Análisis estructural de alta resolución de las [FeFe]-hidrogenasas.
Ensayos bioquímicos para medir las velocidades y los sesgos catalíticos.
Modelado computacional para evaluar las interacciones proteico-ambientales y la estabilización del estado de oxidación.

Principales resultados:

Se identificaron diferencias significativas en el sesgo catalítico en tres [FeFe]-hidrogenasas de Clostridium pasteurianum, que abarcan seis órdenes de magnitud.
Se demostró que las interacciones secundarias de proteínas afectan directamente la estabilización y desestabilización de los estados de oxidación del grupo metálico del sitio activo.
Se estableció una correlación entre la estabilización del estado de oxidación específico y la dirección del sesgo catalítico (oxidación de hidrógeno frente a reducción de protones).

Conclusiones:

Las interacciones secundarias de proteínas son un determinante clave del sesgo catalítico en las [FeFe]-hidrogenasas.
Se propone un modelo simple y elegante en el que la estabilización selectiva de los estados de oxidación por el entorno proteico confiere un sesgo catalítico.
Este hallazgo proporciona una comprensión mecanicista de cómo la estructura de la enzima dicta la función en la catálisis de la hidrogenasa.

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