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Descripción de la estructura electrónica de la unidad cis-MoOS en modelos para hidroxilasas de molibdeno
Christian J Doonan1, Nick D Rubie, Katrina Peariso
1The Department of Chemistry and Biological Chemistry, The University of New Mexico, MSC03 20601 University of New Mexico, Albuquerque, New Mexico 87131-0001, USA.
Journal of the American Chemical Society
|December 8, 2007
Resumen
Las hidroxilasas de molibdeno utilizan un sitio cis-MoOS único para la transferencia de oxígeno. Nuevos modelos revelan un orbital redox deslocalizado que influye en el enlace Mo-S y los mecanismos enzimáticos para la oxidación del sustrato.
Área de la Ciencia:
- Química bioorgánica Química bioorgánica.
- Mecanismos de las enzimas.
- Química organometálica Química orgánica de los metales.
Sus antecedentes:
- Las hidroxilasas de molibdeno son enzimas cruciales que catalizan las reacciones de oxidación.
- Utilizan únicamente el agua como fuente de oxígeno para la incorporación del producto.
- Comprender la estructura electrónica de su sitio activo es clave para su función.
Objetivo del estudio:
- Investigar las estructuras electrónicas de las unidades de cis-molibdeno-oxo-sulfuro (MoOS) en nuevos compuestos modelo.
- Para aclarar el papel de estas estructuras electrónicas en los mecanismos de hidroxilasa de molibdeno.
- Para correlacionar los datos espectroscópicos y computacionales con la función enzimática.
Principales métodos:
- Síntesis de nuevos compuestos modelo de la hidroxilasa de molibdeno: CoCp2[TpiPrMoVOS(OPh) ] y TpiPrMoVIOS(OPh).
- Análisis espectroscópico que incluye absorción de rayos X de borde SK y espectroscopia vibratoria.
- Detallado enlace y cálculos de la estructura electrónica.
Principales resultados:
- Identificación de un orbital redox Mo=S pi* LUMO altamente deslocalizado con un carácter significativo de ligando sulfuro.
- Cuantificación de los cambios en el orden de los enlaces Mo-Sulfido con el estado redox a través de la espectroscopia vibratoria.
- Demostración de un orbital molecular redox-activo que impacta significativamente las propiedades de enlace de MoOS y las propiedades del ligando sulfido.
Conclusiones:
- La estructura electrónica del sitio cis-MoOS es redox activa y controla los mecanismos enzimáticos.
- El control orbital, impulsado por la electrónica única del sitio MoOS, rige la oxidación del sustrato.
- El sitio de la enzima oxidada probablemente polariza sustratos y actúa como un sumidero de electrones.
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