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La escisión de los glucósidos por un nuevo mecanismo en las glucuronil hidrolasas insaturadas
Seino A K Jongkees1, Stephen G Withers
1Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, Canada V6T 1Z1.
Journal of the American Chemical Society
|November 4, 2011
Resumen
Las hidrolasas de glucuronilo insaturadas (UGL) utilizan un nuevo mecanismo de hidratación de éter de vinilo para la escisión de enlaces glucosídicos, distinto de las hidrolasas clásicas. Esta vía, crucial en las infecciones bacterianas, ofrece nuevos objetivos terapéuticos.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Enzimología Enzimología.
- Glucobiología Glucobiología.
Sus antecedentes:
- Las glucuronil hidrolasas insaturadas (UGL) son enzimas de la familia 88 de las glucósidos hidrolasas (GH).
- Separan los azúcares insaturados de los oligosacáridos producidos por las liasas de polisacáridos bacterianos.
- Este proceso es vital en las infecciones bacterianas extracelulares y no tiene una contraparte en los mamíferos.
Objetivo del estudio:
- Proporcionar evidencia clara para un nuevo mecanismo propuesto de acción de UGL.
- Investigar el mecanismo catalítico de las UGL, específicamente la vía de hidratación propuesta del éter vinílico.
- Para diferenciar el mecanismo de UGL de los mecanismos clásicos de hidrolasa.
Principales métodos:
- Análisis del producto de las reacciones catalizadas por UGL en H2O, D2O y metanol diluido/agua.
- Prueba de la actividad de UGL en los tioglucósidos y en los glucósidos de configuración anómica invertida.
- Evaluación de la hidratación catalizada por UGL de un análogo de C-glucósido.
- Medición de los efectos del isótopo cinético β-secundario.
Principales resultados:
- Se demostró que las UGL catalizan la hidratación de los grupos de éter vinílico, lo que lleva a la escisión de los enlaces glucosídicos.
- Los sustratos resistentes a las glicosidasas clásicas, como los tioglucósidos, fueron rápidamente escindidos por las UGL.
- Un análogo de C-glucósido se sometió a hidratación, apoyando un mecanismo iniciado por la hidratación.
- Un pequeño efecto de isótopo cinético β-secundario indicó un estado de transición de iones de oxocarbenio.
Conclusiones:
- El estudio valida un nuevo mecanismo de hidratación de éter vinílico para UGLs.
- Este mecanismo es distinto de invertir o retener los mecanismos directos de la hidrolasa en el carbono anómero.
- Los hallazgos proporcionan una comprensión más profunda de la función de la UGL en la patogénesis bacteriana.
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