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Las estructuras cristalinas de estelacianina oxidada y reducida de las raíces de rábano picante
Michael Koch1, Milko Velarde, Mark D Harrison
1Abteilung Strukturforschung, Max-Planck-Institut für Biochemie, Am Klopferspitz 18, D-82152 Martinsried, Germany.
Journal of the American Chemical Society
|January 6, 2005
Resumen
La umecianina (UMC), una copredoxina vegetal, tiene sus estructuras cristalinas determinadas. Sus características superficiales únicas y su sitio activo sugieren un papel en la transferencia de electrones entre proteínas.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Biología Estructural Biología estructural.
- Ciencia de las proteínas Ciencia de las proteínas.
Sus antecedentes:
- La umecianina (UMC) es una proteína de cobre tipo 1 de la subclase de las estelacianinas de las fitocianinas.
- Las fitocianinas son una familia ubicua de cupredoxinas vegetales involucradas en la transferencia de electrones.
Objetivo del estudio:
- Para determinar las estructuras cristalinas de la umecianina oxidada (Cu(II)) y reducida (Cu(I))
- Para aclarar la base estructural de la función de la umecianina en la transferencia de electrones.
Principales métodos:
- Se utilizó cristalografía de rayos X para determinar las estructuras de Cu(II) y Cu(I) UMC a alta resolución (1.9 y 1.8 A).
- Análisis comparativo del sitio activo y las características de la superficie entre las formas oxidadas y reducidas.
Principales resultados:
- El pliegue general de UMC es similar al de otras fitocianinas.
- El sitio activo presenta una geometría tetraédrica distorsionada para Cu(II) y una geometría piramidal trigonal para Cu(I).
- UMC carece de un parche hidrofóbico cerca del sitio activo, pero posee un gran parche ácido superficial, lo que lo distingue de otras cupredoxinas.
Conclusiones:
- Se producen cambios estructurales limitados en el sitio activo tras los cambios redox, similares a los sitios de cobre tipo 1 con ligandos Met axial.
- Las características únicas de la superficie y la estructura del sitio activo sugieren un papel para la umecianina en la transferencia de electrones entre proteínas.
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