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Dithiomethylether como un ligando en el grupo h de la hidrogenasa

Arti S Pandey¹, Travis V Harris, Logan J Giles

¹Department of Chemistry and Biochemistry and Astrobiology Biogeocatalysis Research Center, Montana State University, Bozeman, Montana 59717, USA.

Journal of the American Chemical Society

|March 8, 2008

Resumen

La cristalografía de rayos X de alta resolución de [FeFe]-hidrogenasa revela el ligando del racimo H. La teoría funcional de la densidad sugiere que se prefiere el etilemétil éter al etilemétil amonio para la producción de hidrógeno.

Área de la Ciencia:

La bioquímica es la bioquímica.
Biología Estructural Biología estructural.
Química computacional es la química computacional.

Sus antecedentes:

La [FeFe]-hidrogenasa es una enzima crucial para la producción biológica de hidrógeno.
El cúmulo H contiene un ligando no proteínico único de ditiolato con implicaciones para la catálisis.
Estudios previos no han determinado definitivamente la composición del ligando.

Objetivo del estudio:

Para determinar la composición exacta del ligando ditiolatado no proteico del grupo H en la [FeFe]-hidrogenasa de Clostridium pasteurianum.
Investigar las implicaciones mecanicistas de la estructura del ligando en la transferencia de protones durante la catálisis.
Para evaluar computacionalmente la estructura de ligando más probable utilizando la teoría funcional de la densidad.

Principales métodos:

Refinamiento cristalográfico de rayos X de la [FeFe]-hidrogenasa a una resolución de 1,39 A.
Teoría funcional de densidad secuencial (DFT) optimizaciones del ligando ditiolatado dentro de un entorno proteico (3.5-3.9 A).
Análisis de factores estructurales, conformacionales y energéticos para evaluar candidatos a ligandos.

Principales resultados:

Se obtuvo la estructura de mayor resolución de [FeFe]-hidrogenasa hasta la fecha.
Las optimizaciones de DFT proporcionaron una evaluación imparcial de la composición del ligando ditiolatado.
Dithiomethylether fue identificado como el ligando preferido del grupo H, mientras que dithiomethylammonium fue desfavorecido como una base catalítica.

Conclusiones:

El estudio proporciona información crítica sobre la composición del ligando del cúmulo H, que influye en su estructura electrónica y actividad catalítica.
Dithiomethylether es fuertemente favorecido como el ligando H-cluster, impactando el mecanismo de la enzima.
Los hallazgos son desfavorables para el metilamonio como base catalítica en la producción de hidrógeno por esta enzima.

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