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Espectroscopia de RMN de estado sólido de 43Ca de abundancia natural en el hueso

Jiadi Xu¹, Peizhi Zhu, Zhehong Gan

¹Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, USA.

Journal of the American Chemical Society

|August 5, 2010

Resumen

Este estudio demuestra la abundancia natural de 43Ca en la RMN giratoria de ángulo mágico en hueso, revelando entornos de calcio distintos en comparación con los modelos de minerales óseos. Estos hallazgos avanzan en la comprensión del calcio.

Área de la Ciencia:

Espectroscopia de RMN en estado sólido.
Biomineralización ósea de los huesos.
Química de la coordinación del calcio.

Sus antecedentes:

Comprender el papel del calcio en la salud ósea requiere información estructural detallada.
Estudios anteriores sobre la estructura ósea se enfrentaron a desafíos de alta resolución.
La RMN de estado sólido en compuestos modelo avanzó en la investigación de minerales óseos, pero la aplicación de RMN de 43Ca estaba limitada por la baja sensibilidad y la abundancia natural.

Objetivo del estudio:

Para demostrar la abundancia natural de 43Ca girando ángulo mágico (MAS) experimentos de RMN en hueso.
Para caracterizar el entorno de coordinación del calcio en el hueso cortical.
Para comparar los entornos de calcio óseo con compuestos modelo como la hidroxiapatita y la apatita carbonatada.

Principales métodos:

Realizó experimentos de RMN MAS de 43Ca de abundancia natural en hueso cortical bovino en polvo.
Se analizaron los espectros de RMN de 43Ca en comparación con la hidroxiapatita y la apatita carbonatada.
Utilizó la espectroscopia Raman para obtener información estructural complementaria.
Se realizó RMN 2D triple cuántica 43Ca MAS en mezclas de apatita carbonatada y osteocalcina.

Principales resultados:

Los espectros de RMN de 43Ca del hueso cortical diferían significativamente de la hidroxiapatita y la apatita carbonatada.
La espectroscopia Raman indicó que los entornos de calcio óseo son más similares a la apatita carbonatada.
El hueso cortical exhibió una mayor constante de acoplamiento cuádrupolo que los compuestos modelo.
El aumento de la concentración de carbonato se correlacionó con la disminución de la frecuencia de desplazamiento químico 43Ca.
La RMN 2D reveló sitios de calcio libre y unidos a proteínas en mezclas de proteína ósea.

Conclusiones:

La RMN 43Ca MAS de abundancia natural es factible para el estudio de la estructura ósea.
El entorno de coordinación de calcio del hueso difiere de la hidroxiapatita pura y la apatita carbonatada.
El estudio proporciona información sobre la unión del calcio en los huesos y su interacción con proteínas como la osteocalcina.

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