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Protonación de un ligando de cobre de histidina en el plastocanino de helecho
Rinske Hulsker1, Annabelle Mery, Ellen A Thomassen
1Leiden Institute of Chemistry, Leiden University, Gorlaeus Laboratories, P.O. Box 9502, 2300 RA, Leiden, The Netherlands.
Journal of the American Chemical Society
|March 21, 2007
Resumen
La plastocyaninina de la helecha es un compuesto plástico.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- La investigación de la fotosíntesis en la investigación de la fotosíntesis.
- Análisis de la estructura y función de las proteínas Análisis de la estructura y función de las proteínas
Sus antecedentes:
- La plastocianina es un portador de electrones clave en la fotosíntesis.
- Un pH bajo afecta la actividad redox de la plastocaniana a través de la protonación de la histidina.
- Anteriormente se pensaba que la protonación His90 de la plastocyanin de la albahaca estaba ausente.
Objetivo del estudio:
- Investiga la protonación His90 de la plastocyanin del helecho a un pH bajo.
- Prueba de las funciones propuestas de Phe12 y Gly36 en la prevención de la protonación.
- Aclarar las discrepancias entre los datos de la solución y la estructura cristalina.
Principales métodos:
- Expresión y purificación de proteínas recombinantes.
- Espectroscopía de Resonancia Magnética Nuclear (RMN) Espectroscopía de Resonancia Magnética Nuclear (RMN) Espectroscopía de Resonancia Magnética Nuclear (RMN) Espectroscopía de Resonancia Magnética Nuclear (RMN) Espectroscopía de Resonancia Magnética Nuclear (RMN) Espectroscopía de Resonancia Magnética Nuclear (RMN) Espectroscopía de Resonancia Magnética Nuclear (RMN) Espectroscopía de Resonancia Magnética Nuclear (RMN).
- Cristalografía de rayos X y voltametría cíclica.
Principales resultados:
- El plastocyanin de helecho de tipo salvaje exhibe la protonación His90 en solución (pKa 4.4).
- Las mutaciones Phe12Leu y Gly36Pro no alteraron el comportamiento de la protonación.
- Las estructuras cristalinas no revelaron la protonación His90, lo que sugiere una interferencia de contacto con el cristal.
Conclusiones:
- La protonación His90 en la plastocyanin del helecho ocurre en la solución, al contrario de los informes anteriores.
- Las interacciones de Phe12 y Gly36 no impiden la protonación de His90.
- La cristalografía puede no reflejar con precisión el comportamiento de la solución para la protonación de plastocanina de helecho.
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