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Identification and Characterization of Protein Glycosylation using Specific Endo- and Exoglycosidases
Published on: December 26, 2011
O-GlcNAcase cataliza la escisión de los tioglucósidos sin la catálisis ácida general
Matthew S Macauley1, Keith A Stubbs, David J Vocadlo
1Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6.
Journal of the American Chemical Society
|December 8, 2005
Resumen
O-GlcNAcase hidroliza eficientemente los tioglucósidos, desafiando las suposiciones anteriores sobre la resistencia a la glucosidasa. Esta enzima actúa como un catalizador bifuncional, estabilizando los estados de transición para la escisión tanto de O- como de S-glucósido.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Enzimología Enzimología.
Sus antecedentes:
- O-GlcNAcase elimina la N-acetilglucosamina de las proteínas mediante catálisis asistida por sustrato y catálisis ácido/base general.
- Los tioglucósidos son generalmente resistentes a la hidrólisis por las glicosidasas.
Objetivo del estudio:
- Para investigar el mecanismo catalítico de O-GlcNAcase en los tioglucósidos.
- Para comparar la hidrólisis de O-glucósidos y S-glucósidos por O-GlcNAcaso.
Principales métodos:
- Análisis de Brønsted y estudios de actividad del pH.
- Efectos del isótopo cinético alfa-deuterio y análisis tipo Taft.
Principales resultados:
- O-GlcNAcase hidroliza eficientemente los S-glucósidos sin una catálisis ácida general.
- La hidrólisis de los tioglucósidos implica la estabilización de los estados de transición tardía con una mayor participación nucleofílica del grupo 2-acetamido.
- El caso O-GlcNA presenta una competencia catalítica similar tanto para los glucósidos O- como para los S-glucósidos.
Conclusiones:
- O-GlcNAcase es un catalizador bifuncional capaz de dividir los tioglucósidos.
- La capacidad de la enzima para dividir los tioglucósidos puede tener implicaciones biológicas significativas.
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