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Identificación de los conductos térmicos que vinculan la interfaz proteína-agua con el bucle del sitio activo y la
Emily J Thompson1,2, Adhayana Paul1,2, Anthony T Iavarone1,2
1Department of Chemistry, University of California, Berkeley, California 94720, United States.
Journal of the American Chemical Society
|January 4, 2021
Resumen
La movilidad de las proteínas es crucial para la catálisis enzimática. Modificación de la enolasa de levadura
Área de la Ciencia:
- La bioquímica
- Cinética de las enzimas
- Dinámica de las proteínas
Sus antecedentes:
- La enolasa de levadura es una liasa conservada con un dominio de barril TIM.
- La movilidad de las proteínas influye en la catálisis enzimática y la reactividad química.
- Comprender las relaciones entre la función de la proteína y el movimiento de la enzima es clave.
Objetivo del estudio:
- Investigar el papel de la movilidad de las proteínas en la catálisis de la enolasa de levadura.
- Examinar cómo las mutaciones específicas del sitio afectan la flexibilidad y la actividad de las enzimas.
- Relacione la dinámica de las proteínas con la reactividad química en las superfamilias de enzimas.
Principales métodos:
- Mutagénesis dirigida al sitio para crear variantes entálpicamente obstaculizadas (por ejemplo, Leu343Ala).
- Ensayos cinéticos de enzimas, incluidos los perfiles de velocidad del pH y los efectos del isótopo de deuterio.
- Espectrometría de masa de intercambio de hidrógeno y deuterio (HDX-MS) para mapear los cambios en la flexibilidad de las proteínas.
Principales resultados:
- Las mutaciones en Leu343 alteraron la hidrofobidad de la cadena lateral, afectando la base catalítica pKa.
- La abstracción de protones que determina la velocidad se mantuvo sin cambios, indicada por efectos similares de isótopos de deuterio.
- Las mutaciones indujeron cambios localizados en la flexibilidad de la proteína, impactando la dinámica del bucle del sitio activo.
- La actividad y la energía de activación mostraron una respuesta discontinua al volumen de la cadena lateral.
Conclusiones:
- La movilidad de las proteínas, especialmente en redes específicas, es vital para una catálisis enzimática eficiente.
- Las redes de largo alcance accesibles al disolvente juegan un papel en la sintonización de las interacciones de los reactivos.
- Los movimientos de proteínas selectivas del sitio son parte integral del mecanismo catalítico de la enzima.
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