Ajuste de las propiedades termoquímicas y cinéticas del ascorbato por su entorno local: química de la solución y implicaciones bioquímicas
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A Rapid and Specific Microplate Assay for the Determination of Intra- and Extracellular Ascorbate in Cultured Cells
Published on: April 11, 2014
Jeffrey J Warren1, James M Mayer
1Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195-1700, USA. jjw82@u.washington.edu
Journal of the American Chemical Society
|May 19, 2010
Resumen
Las tasas de oxidación de la vitamina C (ascorbato) cambian significativamente con su entorno. Los aditivos en las soluciones de acetonitrilo alteran el poder reductor del ascorbato, afectando las reacciones biológicas de transferencia de átomos de hidrógeno.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Química Física es la química física.
- Química orgánica es la química orgánica.
Sus antecedentes:
- El ascorbato (vitamina C) es un cofactor biológico crucial.
- Las reacciones in vivo a menudo ocurren en entornos no acuosos o de interfaz, a diferencia de las soluciones acuosas ampliamente estudiadas.
- Comprender el comportamiento del ascorbato en diversos microambientes es vital para la relevancia biológica.
Objetivo del estudio:
- Investigar el impacto de los entornos locales en las tasas de oxidación de los derivados de ascorbato y la termodinámica.
- Para explorar cómo los aditivos en el acetonitrilo afectan el poder reductor del ascorbato.
- Aclarar el mecanismo y el origen de los efectos observados de los disolventes en la transferencia de átomos de hidrógeno.
Principales métodos:
- Oxidación de dos derivados del ascorbato utilizando el radical TEMPO en el acetonitrilo.
- Variación sistemática de la polaridad de la solución mediante la adición de agua y otros solutos polares.
- Medición de la velocidad de reacción y las constantes de equilibrio.
- Análisis de la correlación entre las constantes de tasa y de equilibrio.
Principales resultados:
- Las tasas de oxidación y las fuerzas impulsoras de los derivados de ascorbato fueron altamente sensibles a los aditivos en el acetonitrilo.
- La adición de agua y solutos polares alteró significativamente el poder reductor del ascorbato.
- Los efectos observados fueron impulsados termoquímicamente, no puramente cinético.
- Esto contrasta con los efectos de disolventes reportados anteriormente sobre la transferencia de átomos de hidrógeno.
Conclusiones:
- Los factores ambientales locales, como la polaridad del disolvente, influyen profundamente en el potencial redox del ascorbato.
- Los hallazgos destacan un efecto único del disolvente termoquímico en las reacciones de transferencia de átomos de hidrógeno.
- Estos resultados tienen implicaciones potenciales para la comprensión de las reacciones biológicas que involucran al ascorbato en diversos microambientes celulares.
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