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El panorama energético dinámico del dihidrofolato reduce la catálisis de la reductasa
David D Boehr1, Dan McElheny, H Jane Dyson
1Department of Molecular Biology and Skaggs Institute for Chemical Biology, Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
Science (New York, N.Y.)
|September 16, 2006
Resumen
Los investigadores estudiaron los subestados conformacionales de las enzimas utilizando resonancia magnética nuclear. La unión de ligandos guía a la enzima a través de su ciclo de reacción mediante la modulación de paisajes energéticos y estados conformacionales excitantes.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Enzimología Enzimología.
- Biología Estructural Biología estructural.
Sus antecedentes:
- La comprensión de los mecanismos de reacción enzimática es crucial para el desarrollo de fármacos.
- La dihidrofolato reductasa de Escherichia coli (EcDHFR) es una enzima clave en el metabolismo del folato.
- La caracterización de la dinámica conformacional de las enzimas proporciona información sobre la eficiencia catalítica.
Objetivo del estudio:
- Para investigar subestados conformacionales de mayor energía de Escherichia coli dihidrofolato reductasa.
- Aclarar el papel de estos estados secundarios en el intercambio de sustrato/cofactor y en la catálisis.
- Para entender cómo la unión de ligandos influye en la vía de reacción de la enzima.
Principales métodos:
- Se empleó la espectroscopia de dispersión de relajación por resonancia magnética nuclear (RMN).
- Caracterización de subestados conformacionales transitorios de mayor energía.
- Análisis de los intermediarios enzimáticos durante el ciclo catalítico.
Principales resultados:
- Cada intermedio catalítico muestra estados excitados bajos.
- Las conformaciones de estos estados excitados se asemejan a los intermedios adyacentes en el ciclo.
- El intercambio de sustrato y cofactor ocurre a través de estos estados excitados.
- Las tasas de transferencia y rotación de hidrógenos dependen de las transiciones de estado de tierra a estado excitado.
Conclusiones:
- La modulación inducida por ligandos del paisaje energético de la enzima dirige la vía de reacción.
- Los subestados conformacionales excitados son críticos para una catálisis enzimática eficiente.
- La enzima navega su ciclo de reacción a través de un paisaje de energía dinámicamente canalizado.
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