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Transferencia de electrones acoplados a protones en el fotosistema II: inventario de protones de una tirosina redox
David L Jenson1, Bridgette A Barry
1School of Chemistry and Biochemistry and the Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.
Journal of the American Chemical Society
|July 10, 2009
Resumen
El fotosistema II es el fotossistema II.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- La investigación de la fotosíntesis en la investigación de la fotosíntesis.
- Biofísica de las proteínas Biofísica de las proteínas.
Sus antecedentes:
- El fotosistema II (PSII) es crucial para la fotosíntesis, que implica la oxidación del agua y la reducción de la plastoquinona.
- Los polipéptidos D1 y D2 forman el núcleo de PSII, con el complejo de evolución del oxígeno (OEC) responsable de la oxidación del agua.
- La tirosina Y ((D) está implicada en la estabilización de la OEC y exhibe transferencia de electrones acoplados a protones (PCET) con histidina 189.
Objetivo del estudio:
- Investigar el mecanismo de la transferencia de electrones acoplados a protones (PCET) Y(D) en el fotosistema II a un pH alto.
- Para dilucidar las vías de transferencia de protones involucradas en las reacciones redox Y(D).
Principales métodos:
- Utilizó la técnica de inventario de protones para analizar Y(D) PCET a un pH alto.
- Aplicado etiquetado isotópico y mutagénesis dirigida en el sitio en trabajos anteriores para asignar Y (((D) y estudiar sus interacciones.
Principales resultados:
- Los datos del inventario de protones exhibieron hipercurvatura, lo que indica múltiples vías de donación de protones a Y(D)(*).
- Al menos una vía implica la transferencia de más de un protón.
- El mecanismo PCET en pH alto es más complejo de lo que se entendía anteriormente.
Conclusiones:
- Los hallazgos revelan una intrincada dinámica de transferencia de protones en el PCET Y(D) del Fotosistema II.
- Múltiples vías de protones, incluidas las transferencias de múltiples protones, son esenciales para la función Y ((D) a un pH alto.
- Este estudio avanza en nuestra comprensión de los mecanismos moleculares subyacentes a la oxidación fotosintética del agua.
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