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Nucleoside Triphosphates - From Synthesis to Biochemical Characterization
Published on: April 3, 2014
El complejo dinuclear Zn(II) promueve la escisión y la isomerización de los fosfatos de 2-hidroxipropilo alquilo por
Wing Yin Tsang1, David R Edwards, Stephanie A Melnychuk
1Department of Chemistry, Queen's University, Kingston, Ontario, Canada K7L 3N6.
Journal of the American Chemical Society
|March 19, 2009
Resumen
Este estudio investiga la escisión catalítica de un éster fosfato mediante el uso de un complejo di-Zn (II) complejo. La reacción forma productos isoméricos, que luego se isomerizan a una mezcla termodinámica a través de un intermediario cíclico, revelando información sobre los mecanismos de hidrólisis de los ésteres fosfatados.
Área de la Ciencia:
- Coordinación Química de la Coordinación
- Química organometálica Química orgánica de los metales.
- La cinética de la reacción.
Sus antecedentes:
- La hidrólisis de ésteres de fosfato es crucial en los sistemas biológicos y químicos.
- La comprensión de los mecanismos de la escisión del fosfato catalizado por metales informa el diseño del catalizador.
- El complejo di-Zn ((II) de bis-1,3-N1,N1'- ((1,5,9-triazaciclododecil) propano (4) se investiga por su actividad catalítica.
Objetivo del estudio:
- Para dilucidar la cinética y los productos de escisión de 2-hidroxipropil p-nitrofenil fosfato catalizado por el complejo 4.
- Determinar el mecanismo de isomerización entre mezclas de productos cinéticos y termodinámicos.
- Para investigar el papel de un intermediario de fosfato cíclico en la vía de reacción.
Principales métodos:
- Espectroscopia de RMN de 1H dependiente del tiempo para monitorear el progreso de la reacción e identificar intermedios / productos.
- Estudios cinéticos para determinar las constantes de velocidad y la eficiencia catalítica (kcatmax).
- Análisis de tramas de Brønsted para comprender las características del estado de transición.
Principales resultados:
- La reacción se produce a través de un fosfato cíclico (4-metiletileno fosfato, 2).
- Se forma una mezcla cinética de 2-hidroxipropil metilfosfato (3) y 1-hidroxipropan-2-il metilfosfato (3a) (razón 29/71).
- El complejo 4 cataliza la isomerización de la mezcla cinética a una mezcla termodinámica (72/28 3/3a) a través del intermediario cíclico 2.
- Se obtuvo una gráfica lineal de Brønsted (log kcatmax vs. sspKa) con una pendiente de -0.85, lo que indica un ~45% de escisión de enlace P-O en el estado de transición.
Conclusiones:
- El complejo di-Zn(II) (4) cataliza eficazmente la hidrólisis y la isomerización de los ésteres de fosfato.
- El mecanismo de reacción implica un intermediario de fosfato cíclico, que influye en la distribución del producto final.
- El gráfico de Brønsted proporciona evidencia para el grado de escisión de los bonos P-O en el estado de transición, apoyando un mecanismo concertado o escalonado.
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