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Los campos eléctricos extremos catalizan la energía en el sitio activo de la isomerasa cetosteroide

Stephen D Fried¹, Sayan Bagchi¹, Steven G Boxer²

¹Department of Chemistry, Stanford University, Stanford, CA 94305-1052, USA.

Science (New York, N.Y.)

|December 20, 2014

Resumen

Las enzimas utilizan campos eléctricos para acelerar las reacciones. Los investigadores cuantificaron el campo electrostático en la isomerasa cetosteroide (KSI), vinculando su fuerza a la mejora catalítica y revelando la contribución electrostática a la función de la enzima.

Área de la Ciencia:

La bioquímica es la bioquímica.
Física Química Física Química es la física de la química.
Enzimología Enzimología.

Sus antecedentes:

Las enzimas emplean campos electrostáticos para la catálisis, pero cuantificar estos campos y su contribución precisa a las velocidades de reacción sigue siendo un desafío.
Los métodos experimentales estándar tienen dificultades para medir la magnitud de los campos eléctricos dentro de los sitios activos de la enzima.

Objetivo del estudio:

Para cuantificar la intensidad del campo eléctrico dentro del sitio activo de la ketosteroide isomerasa (KSI).
Para determinar la correlación entre el campo eléctrico del sitio activo y la mejora de la velocidad catalítica de KSI.
Para dilucidar la contribución electrostática a la catálisis enzimática.

Principales métodos:

Se empleó la espectroscopia vibratoria del efecto Stark para medir los campos eléctricos.
La frecuencia vibratoria del enlace C=O fue monitoreada para sondear el campo eléctrico.
Las tasas catalíticas de KSI se midieron en diferentes condiciones.

Principales resultados:

El sitio activo de la cetosteroide isomerasa (KSI) genera un campo eléctrico sustancial en el enlace C=O.
Se observó una fuerte correlación entre la magnitud del campo eléctrico y el aumento de la velocidad catalítica de la enzima.
Se cuantificó la fracción de catálisis atribuible a la electrostática.

Conclusiones:

Los sitios activos de las enzimas pueden generar poderosos campos eléctricos que impactan significativamente la química del sustrato.
La espectroscopia vibratoria del efecto Stark proporciona una medida cuantitativa de la electrostática en la catálisis enzimática.
Estos hallazgos ofrecen información sobre el papel de la electrostática en la función de las enzimas y otros sistemas biomoleculares.

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