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Efectos de la identidad y posición del sitio de carga catiónica en la disociación por transferencia de electrones de
Yu Xia1, Harsha P Gunawardena, David E Erickson
1Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-2084, USA.
Journal of the American Chemical Society
|September 21, 2007
Resumen
El sitio de la carga catiónica tiene un impacto significativo en las reacciones de iones/iones de la fase gaseosa en los péptidos. La histidina protonada favorece la transferencia de electrones sin disociación, mientras que la arginina y la lisina muestran patrones distintos de fragmentación de la cadena lateral.
Área de la Ciencia:
- Química analítica Química analítica es un campo de estudio de la química analítica.
- Química Física es la química física.
- La bioquímica es la bioquímica.
Sus antecedentes:
- Las reacciones de iones/iones en la fase gaseosa son cruciales para el análisis de péptidos.
- Comprender los mecanismos de reacción como la transferencia de protones (PT) y la transferencia de electrones (ET) es clave.
- La ubicación del sitio de carga catiónica influye en las vías de reacción y la formación de productos.
Objetivo del estudio:
- Para investigar el efecto del sitio de carga catiónica en las reacciones de iones/iones en la fase gaseosa.
- Examinar cuantitativamente la partición del producto en canales de reacción competidores.
- Aclarar los mecanismos de la disociación por transferencia de electrones (ETD) y la disociación por captura de electrones (ECD).
Principales métodos:
- Utilizando péptidos modelo de protonación múltiple y aniones de carga única.
- Analizando la partición del producto en PT, ET, ETD y ET sin canales de disociación (ET, no D).
- Comparando los patrones de fragmentación, incluidas las escisiones de vínculos de la columna vertebral frente a las de la cadena lateral.
Principales resultados:
- Los cationes péptidos con lisina, arginina e histidina protonadas exhibieron ET más alto que los sitios de carga fija.
- La histidina protonada mostró la ET más alta, sin D; la lisina / arginina carecía de productos ET intactos.
- Los cationes de arginina produjeron la mayor cantidad de pérdidas en la cadena lateral, seguidos por la histidina, luego la lisina.
Conclusiones:
- La identidad y la posición del sitio de carga catiónica influyen significativamente en las vías de ET y fragmentación.
- La identidad del reactivo aniónico también afecta a PT y a las fracciones de pérdida de cadena lateral.
- Múltiples mecanismos contribuyen a los productos observados de ETD / ECD, modulados por el sitio de carga y el reactivo.
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