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Quantifying the Binding Interactions Between Cu(II) and Peptide Residues in the Presence and Absence of Chromophores
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Evidencia de la interacción catión-pi entre Cu2+ y el triptófano
Hanami Yorita1, Kohei Otomo, Hirotsugu Hiramatsu
1Graduate School of Pharmaceutical Sciences, Tohoku University, Aobayama, Sendai 980-8578, Japan.
Journal of the American Chemical Society
|October 23, 2008
Resumen
Este estudio proporciona la primera evidencia espectral de las interacciones catión-pi entre los iones de cobre (Cu2+) y triptófano (Trp). Estas interacciones, observadas en un motivo de proteína, son detectables a través del dicroísmo circular y la espectroscopia de absorción UV.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- La espectroscopia es una técnica de espectroscopia.
- Estructura de las proteínas Estructura de las proteínas
Sus antecedentes:
- Las interacciones catión-pi son fuerzas no covalentes cruciales en las estructuras y funciones moleculares.
- Los cationes de metales de transición como Cu2+ suelen excluirse de las interacciones catión-pi debido a preocupaciones de oxidación y covalencia.
Objetivo del estudio:
- Proporcionar la primera evidencia espectral de la interacción catión-pi entre Cu2+ y triptófano (Trp).
- Para caracterizar las firmas espectrales de esta interacción utilizando el dicroísmo circular (CD) y la absorción UV.
Principales métodos:
- Espectroscopia de dicroísmo circular (CD) para detectar cambios espectrales.
- Espectroscopia de absorción UV para observar los cambios de intensidad.
- Mutagénesis dirigida al sitio y sustitución iónica para confirmar la interacción.
Principales resultados:
- Se observó una banda negativa distinta a 223 nm en los espectros de CD para la interacción Cu2+-Trp.
- La absorción UV mostró cambios característicos de intensidad a 222/231 nm.
- Las señales espectrales desaparecieron con la mutación / agotamiento de Trp o el reemplazo de Cu2 + por Ni2 +.
Conclusiones:
- El estudio presenta la primera evidencia espectral de la interacción catión-pi entre Cu2+ y Trp.
- La banda de CD observada a 223 nm puede servir como un marcador para las interacciones Cu2+-Trp catión-pi.
- La coordinación de los ligandos cargados negativamente con Cu2+ puede facilitar las interacciones catión-pi.
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