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Dinámica y energética del disolvente en solución en la catálisis enzimática: la reacción S(N) 2 de la deshalogenasa
Mats H M Olsson1, Arieh Warshel
1University of Southern California, 3620 McClintock Avenue, Department of Chemistry, SGM418, Los Angeles, California 90089-1062, USA. molsson@usc.edu
Journal of the American Chemical Society
|November 19, 2004
Resumen
La catálisis enzimática se puede entender viendo la enzima como un disolvente. Para la dehalogenasa de haloalcanos (DhlA), el efecto catalítico proviene principalmente de la preorganización del disolvente de proteínas, no de la desolución.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- La cinética de las enzimas.
- Química computacional es la química computacional.
Sus antecedentes:
- La catálisis enzimática a menudo se analiza considerando la enzima como un disolvente eficaz para sustratos.
- Comprender las contribuciones energéticas y dinámicas a la catálisis enzimática es crucial para el esclarecimiento del mecanismo.
Objetivo del estudio:
- Para analizar la enzima haloalcan deshalogenasa (DhlA) utilizando el modelo de la enzima como disolvente.
- Evaluar las contribuciones energéticas y dinámicas al efecto catalítico de DhlA.
- Para diferenciar los efectos catalíticos observados de los mecanismos de desolución propuestos.
Principales métodos:
- Análisis computacional de la reacción S(N) 2 catalizada por la haloalcana deshalogenasa (DhlA).
- Investigación de la energética y dinámica de las coordenadas del disolvente dentro del sitio activo de la enzima.
- Comparación de los efectos del disolvente ligado a las enzimas con los de la solución a granel.
Principales resultados:
- La contribución catalítica primaria surge de la preorganización de las coordenadas proteína-solvente.
- El estado de transición es más efectivamente "solvado" por la enzima que en solución.
- Los efectos dinámicos contribuyen mínimamente a la catálisis global, independientemente de la definición.
- Las diferencias en los tiempos de relajación del disolvente tienen un impacto trivial en comparación con los cambios de energía libre de reorganización.
Conclusiones:
- La catálisis enzimática por DhlA está dominada por la preorganización del entorno del sitio activo, que actúa como un disolvente específico.
- El mecanismo es distinto de la hipótesis de desolvación comúnmente propuesta.
- Los efectos dinámicos juegan un papel menor en la eficiencia catalítica de esta enzima.
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