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Published on: January 3, 2018
Anisotropías del tensor de susceptibilidad magnética para una serie de iones lantánidos en una matriz proteica fija
I Bertini1, M B Janik, Y M Lee
1Department of Chemistry, University of Florence, Via Gino Capponi 9, 50121, Florence, Italy.
Journal of the American Chemical Society
|July 18, 2001
Resumen
Los iones lantánidos se incorporaron a la calbindina D ((9k), revelando entornos de coordinación consistentes. Este estudio valida la teoría de Bleaney para los complejos de lantánidos en solución, ofreciendo información sobre las propiedades magnéticas.
Área de la Ciencia:
- Química biofísica y bioquímica.
- Biología Estructural Biología estructural.
- Química de los Lantánidos
Sus antecedentes:
- Los iones lantánidos sirven como sondas en los sistemas biológicos, pero sus entornos de coordinación y propiedades magnéticas en las proteínas no se comprenden completamente.
- Calbindina D ((9k) es una proteína de unión al calcio que puede acomodar varios iones lantánidos en sus sitios de unión.
Objetivo del estudio:
- Investigar el entorno de coordinación y las propiedades magnéticas de una serie de iones lantánidos en la proteína de unión al calcio calbindina D ((9k).
- Evaluar experimentalmente la teoría de Bleaney para los complejos de lantánidos en solución utilizando un entorno de proteínas consistente.
Principales métodos:
- Incorporación de iones lantánidos (excepto Pm y Gd) en el sitio de unión del calcio C-terminal de la calbindina D ((9k).
- La espectroscopia de Resonancia Magnética Nuclear (RMN), específicamente los experimentos de Coherencia Cuántica Heteronuclear Única (HSQC), para medir los cambios químicos.
- Estimación de los desplazamientos de pseudocontacto (PCS) restando las contribuciones diamagnéticas de los derivados de La (III) y Lu (III).
- Determinación simultánea de la estructura utilizando los datos del Efecto Nuclear Overhauser (NOE) del derivado Ce (III) y los datos de PCS de todos los lantánidos.
Principales resultados:
- Se mantuvo un entorno de coordinación consistente en toda la serie de lantánidos dentro de la calbindina D ((9k).
- Un gran número de señales de RMN permitió la asignación exclusiva de desplazamientos hiperfinos al PCS.
- Se determinaron las anisotropías del tensor de susceptibilidad magnética para cada lantánido, mostrando un buen acuerdo con la teoría de Bleaney.
- El estudio confirmó la similitud del entorno de coordinación para todos los lantánidos incorporados.
Conclusiones:
- Los iones lantánidos se pueden utilizar de manera confiable para sondear la estructura y la dinámica de proteínas como la calbindina D ((9k).
- Los resultados proporcionan un fuerte apoyo experimental a la teoría de Bleaney, particularmente con respecto a las propiedades magnéticas de los complejos de lantánidos en solución.
- Este trabajo establece una base para el uso de iones lantánidos como sondas paramagnéticas en sistemas biológicos complejos.
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