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Transferencia de protones a larga distancia con una ruptura en el sitio activo de la bacteriorhodopsina
Prasad Phatak1, Jan S Frähmcke, Marius Wanko
1Institute of Physical and Theoretical Chemistry, TU Braunschweig, D-38106 Braunschweig, Germany.
Journal of the American Chemical Society
|May 2, 2009
Resumen
La transferencia de protones de Bacteriorhodopsin implica un estado transitorio en el que Asp212 se protona, lo que facilita el movimiento de protones. Este estudio utilizó métodos computacionales para explorar este mecanismo en Halobacterium salinarium.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Biología Estructural Biología estructural.
- La biofísica computacional es una biofísica computacional.
Sus antecedentes:
- Bacteriorhodopsin es una bomba de protones impulsada por la luz en Halobacterium salinarium.
- El transporte de protones implica isomerización retiniana y cambios conformacionales.
- El mecanismo de transferencia de protones a larga distancia, especialmente durante el estado O, sigue sin estar claro.
Objetivo del estudio:
- Para investigar el papel de un estado intermedio transitorio que involucra la protonación de Asp212.
- Para dilucidar el mecanismo de la transferencia de protones de larga distancia de Asp85 al grupo de liberación de protones.
- Para evaluar la contribución de Asp212 a la desprotonación de Asp85.
Principales métodos:
- Cálculos de transferencia de protones de la mecánica cuántica híbrida / mecánica molecular (QM / MM).
- Utilizó varias estructuras de proteínas, geometrías de la retina y configuraciones de agua del sitio activo.
- Modelos estructurales validados utilizando energías de excitación UV-vis y frecuencias vibratorias C=O.
Principales resultados:
- Los cálculos sugieren que se muestre un conformador [O] transitorio con Asp212 protonado durante la transferencia de protones.
- Este Asp212 protonado puede participar en la desprotonación de Asp85.
- El estado inicial de transferencia de protones (O) implica una retina retorcida y al menos tres moléculas de agua.
Conclusiones:
- Una protonación transitoria de Asp212 es un intermedio plausible en la vía de transferencia de protones de la bacteriorhodopsina.
- Los hallazgos proporcionan información sobre el mecanismo molecular de la translocación de protones a través de la membrana.
- El modelado computacional es crucial para comprender procesos biomoleculares complejos como el bombeo de protones.
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