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Direct Detection of the Acetate-forming Activity of the Enzyme Acetate Kinase
Published on: December 19, 2011
Estudios espectroscópicos de las interacciones del sustrato con la clavaminato sintasa 2, una enzima multifuncional
J Zhou1, W L Kelly, B O Bachmann
1Contribution from the Departments of Chemistry, Stanford University, Stanford, California 94305, USA.
Journal of the American Chemical Society
|July 27, 2001
Resumen
La clavamanaato sintasa 2 (CS2) utiliza un sitio activo ferroso para catalizar múltiples reacciones oxidativas. La insaturación coordinada del hierro es clave para las reacciones de acoplamiento y la función de las enzimas.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Enzimología Enzimología.
- Biología Estructural Biología estructural.
Sus antecedentes:
- La clavamanaato sintasa 2 (CS2) es una enzima multifuncional crucial para la biosíntesis del ácido clavulánico.
- Cataliza varias reacciones oxidativas utilizando un solo sitio activo ferroso y alfa-cetoglutarato (alfa-KG) como cosubstrato.
Objetivo del estudio:
- Para aclarar las relaciones estructura-función de CS2 durante su ciclo catalítico.
- Investigar el papel de la coordinación del hierro en las diversas actividades enzimáticas de CS2.
Principales métodos:
- Técnicas espectroscópicas que incluyen absorción, dicroísmo circular (CD), dicroísmo circular magnético (MCD) y MCD de temperatura variable y campo variable (VTVH MCD).
- Análisis de las interacciones enzima-substrato y enzima-cosubstrato.
Principales resultados:
- En reposo, el CS2/Fe (II) exhibe un sitio activo de seis coordenadas; el alfa-KG se une con fuerza.
- El sitio activo adquiere cinco coordenadas al unirse tanto al sustrato como al alfa-KG, lo que facilita las reacciones acopladas.
- Los grados variables de las especies ferrosas de seis coordenadas se correlacionan con reacciones no acopladas y desactivación de enzimas.
- Se observan especies ferrosas de cinco coordenadas con estructuras similares en diferentes complejos de sustrato.
Conclusiones:
- La insaturación coordinada del sitio Fe(II) en CS2 es crítica para acoplar la descarboxilación oxidativa alfa-KG a la oxidación del sustrato.
- La regulación enzimática del agua que se une a las especies ferrosas influye en la reactividad.
- La comprensión de estos mecanismos proporciona una visión de la versatilidad catalítica de CS2.
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