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Ex Vivo Red Blood Cell Hemolysis Assay for the Evaluation of pH-responsive Endosomolytic Agents for Cytosolic Delivery of Biomacromolecular Drugs
Published on: March 9, 2013
Nuevo enlace covalente histidina-hemo en una hemoglobina
B Christie Vu1, A Daniel Jones, Juliette T J Lecomte
1Department of Chemistry and the Center for Biomolecular Structure and Function, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Journal of the American Chemical Society
|July 18, 2002
Resumen
La hemoglobina de Synechocystis se somete a la unión de hemo a su cadena polipeptídica a través de una reacción química que involucra al hemo.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Biología Molecular Biología Molecular
- Química de las proteínas química de las proteínas.
Sus antecedentes:
- La hemoglobina recombinante de Synechocystis sp. fue obtenida. PCC 6803 es un sistema modelo para el estudio de las interacciones hemo-proteína.
- La unión del hemo a la globina es crucial para la función de la hemoglobina, pero los mecanismos químicos precisos no se comprenden completamente.
Objetivo del estudio:
- Para dilucidar el mecanismo químico de la unión del hemo a la hemoglobina de Synechocystis.
- Para identificar los grupos de reacción específicos tanto en el hemo como en la proteína.
Principales métodos:
- Espectroscopia de Resonancia Magnética Nuclear (RMN) (1H, homonuclear, 1H-15N) Espectroscopia de Resonancia Magnética Nuclear (RMN) Espectroscopia de Resonancia Magnética Nuclear (RMN) Espectroscopia de Resonancia Magnética Nuclear (RMN) Espectroscopia de Resonancia Magnética Nuclear (RMN) Espectroscopia de Resonancia Magnética Nuclear (RMN) Espectroscopia de Resonancia Magnética Nuclear (RMN) Espectroscopia de Resonancia Magnética Nuclear (RMN) Espectroscopia de Resonancia Magnética Nuclear (RMN) Espectroscopio de Resonancia Magnética Nuclear (RMN) Espectroscopio de Resonancia Magnética Nuclear (RMN) Espectroscopio de Resonancia Magnética Nuclear (RMN) Espectroscopio de Resonancia Magnética Nuclear
- La espectrometría de masas (MS) de los digestos de pepsina.
- Estudios de modificación química utilizando ditionita y porfirinas modificadas.
Principales resultados:
- El tratamiento con ditionita a pH neutro indujo una rápida unión de hemo a la hemoglobina de Synechocystis.
- El grupo 2-vinilo del hemo fue identificado como la fracción reactiva.
- La espectrometría de masas localizó el sitio de adhesión a un péptido C-terminal de 12 meros.
- La RMN identificó Histidina 117 (His117) como el residuo modificado, con Nepsilon del anillo de imidazol reaccionando con el vinilo Calpha. del hemo.
- La modificación no se produjo con la protoporfirina IX de Zn, lo que indica que la reducción del hierro hemo es esencial.
Conclusiones:
- El estudio revela una nueva vía química para la unión del hemo a la globina.
- Esta reacción implica la modificación directa de un residuo de histidina por el grupo vinilo del hemo, facilitada por la reducción inducida por la ditionita.
- Los hallazgos proporcionan información sobre las modificaciones posteriores a la traducción y los mecanismos de enlace cruzado hemo-proteína.
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