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El establecimiento de la competencia cinética de la imina catiónica intermedio en la nitroalcano oxidasa
Michael P Valley1, Shane E Tichy, Paul F Fitzpatrick
1Department of Biochemistry and Biophysics emistry, Texas A&M University, College Station, Texas 77843-2128, USA.
Journal of the American Chemical Society
|February 17, 2005
Resumen
El cianuro inactiva la nitroalcana oxidasa formando adyuctos con el cofactor flavin. Esta reacción ocurre después de la abstracción de protones y antes de la oxidación de la flavina, atrapando un intermediario electrófilo en el mecanismo enzimático.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- La cinética de las enzimas.
- Química orgánica es la química orgánica.
Sus antecedentes:
- La nitroalcana oxidasa es una flavoproteína que cataliza la oxidación del nitroalcano.
- Se sabe que el cianuro inhibe varias enzimas.
Objetivo del estudio:
- Para dilucidar el mecanismo de la inactivación del cianuro de la nitroalcano oxidasa.
- Para identificar las especies intermedias involucradas en el ciclo catalítico de la enzima.
Principales métodos:
- Los estudios de cinética de enzimas estudian la cinética de las enzimas.
- Espectrometría de masas de los aductos de flavinas.
- Mediciones del efecto del isótopo cinético.
Principales resultados:
- El cianuro inactiva la nitroalcana oxidasa a través de la formación de un adducto de flavina (cianoetil/cianohexil).
- La inactivación ocurre después de la abstracción de protones y antes de la oxidación de la flavina, con un efecto de isótopo cinético de 7.9.
- El cianuro atrapa un intermediario electrófilo propuesto en el mecanismo de la enzima.
Conclusiones:
- El mecanismo implica la abstracción de protones del nitroalcano, la adición de carbanión a la flavina, la eliminación del nitrito y la formación de una imina electrofílica.
- La inactivación del cianuro proporciona evidencia de este mecanismo propuesto al atrapar un intermediario clave.
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