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La carga aniónica tiene prioridad sobre la geometría en los análogos de estado de transición del fluoruro de aluminio

Nicola J Baxter¹, G Michael Blackburn, James P Marston

¹Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, United Kingdom.

Journal of the American Chemical Society

|March 6, 2008

Resumen

Los complejos de fluoruro metálico son cruciales para la comprensión de la catálisis enzimática. Este estudio revela que el pH influye en la coordinación del fluoruro, con el fluoruro de magnesio (MgF3-) reemplazando el fluoruro de aluminio (AlF4-) a un pH más alto, lo que afecta la inhibición de las enzimas y los efectos fisiológicos.

Área de la Ciencia:

La bioquímica es la bioquímica.
Catalización de enzimas por catalización de enzimas
Biología Estructural Biología estructural.

Sus antecedentes:

Las reacciones de transferencia de fosforilo son procesos biológicos fundamentales.
Los complejos de fluoruro metálico, particularmente el fluoruro de aluminio (AlFx), sirven como análogos de estado de transición (TSA) en los estudios estructurales de la catálisis enzimática.
Investigaciones anteriores sugirieron una coordinación de fluoruro dependiente del pH en las TSA de fluoruro de aluminio, con la formación de AlF3 por encima del pH 7.0 y AlF4- por debajo.

Objetivo del estudio:

Para investigar la coordinación dependiente del pH del fluoruro en los complejos de metal-fluoruro utilizados como AST.
Para dilucidar el mecanismo detrás de la propuesta de cambio de pH en la coordinación de fluoruro para las enzimas.
Determinar el papel del aluminio y el magnesio en los complejos inhibidores de la enzima-metal fluoruro.

Principales métodos:

19F Se empleó la espectroscopia de Resonancia Magnética Nuclear (RMN) para analizar la coordinación del fluoruro.
Se realizaron estudios estructurales y mecanicistas sobre la beta-fosfoglucomutasa, la fosfoserina fosfatasa y la fosfoglicerato quinasa.

Principales resultados:

El cambio de pH en la coordinación del fluoruro no se debe a la conversión de AlF4 a AlF3.
En cambio, el aumento del pH conduce a la sustitución progresiva de AlF4- por MgF3-.
Las enzimas priorizan la carga aniónica sobre la geometría trigonal nativa en un amplio rango de pH.
En las proporciones fisiológicas de metales, el aluminio puede superar al magnesio en las TSA de fluoruro de metales enzimáticos.

Conclusiones:

La coordinación dependiente del pH observada en los complejos de fluoruro de enzimas y metales implica que MgF3- reemplace a AlF4- a un pH más alto.
Este mecanismo destaca la estrategia de la enzima para mantener la carga aniónica.
El dominio del aluminio sobre el magnesio en los TSA sugiere que puede ser responsable de algunos efectos fisiológicos del fluoruro.

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