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Mecanismo de la bencilsuccinato sintasa probado por el sustrato y el intercambio de isótopos
1Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055, USA.
Journal of the American Chemical Society
|December 15, 2006
Resumen
La bencilsuccinato sintasa (BSS) facilita el metabolismo del tolueno. Los estudios muestran que el BSS puede revertir su reacción, convirtiendo el bencilsuccinato de nuevo en tolueno y fumarato, incluso en contra de un equilibrio desfavorable, revelando conocimientos mecanicistas.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Enzimología Enzimología.
- El metabolismo anaeróbico.
Sus antecedentes:
- La bencilsuccinato sintasa (BSS) es clave en la descomposición anaeróbica del tolueno.
- La enzima cataliza la adición de tolueno al fumarato, formando el (R) -benzilsuccinato.
Objetivo del estudio:
- Para investigar el rango de sustrato y la reacción inversa de BSS.
- Para dilucidar el mecanismo catalítico de BSS.
Principales métodos:
- Pruebas de enzimas utilizando p-cresol y bencilsuccinato marcado con deuterio.
- Análisis de los productos de reacción y el intercambio isotópico.
Principales resultados:
- BSS demostró el intercambio de sustratos, formando (4-hidroxibencil) succinato a partir del p-cresol y el bencilsuccinato.
- La enzima catalizó la reacción inversa desfavorable (bencilsuccinato a tolueno y fumarato) de manera eficiente.
- Se observó un intercambio de deuterio con el disolvente, lo que indica la transferencia de hidrógeno a la proteína.
Conclusiones:
- BSS puede catalizar la reacción inversa, a pesar de la termodinámica desfavorable.
- La evidencia apoya un mecanismo que implica la transferencia de hidrógeno a un residuo de cisteína en el sitio activo.
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