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Dinámica de hidratación específica del sitio en el núcleo no polar de un glóbulo fundido por polarización nuclear
Brandon D Armstrong1, Jennifer Choi, Carlos López
1Department of Physics, University of California-Santa Barbara, Santa Barbara, California 93106, United States.
Journal of the American Chemical Society
|March 30, 2011
Resumen
El núcleo no polar de la apomioglobina.
Área de la Ciencia:
- La biofísica es la biofísica.
- Dinámica de las proteínas Dinámica de las proteínas.
- Biología estructural Biología estructural.
Sus antecedentes:
- El plegamiento de proteínas implica la extrusión de agua desde el núcleo no polar.
- La hidratación de los estados intermedios colapsados de proteínas sigue siendo objeto de debate.
- Las dinámicas de hidratación de proteínas específicas del sitio son difíciles de medir.
Objetivo del estudio:
- Para investigar la dinámica de hidratación de proteínas con resolución específica del sitio.
- Para sondear la dinámica del agua en diferentes estados de apomioglobina (glóbulo fundido, nativo, desplegado).
- Para explorar el papel del agua en los intermediarios de plegamiento de proteínas.
Principales métodos:
- La polarización nuclear dinámica de Overhauser (ODNP) a 0,35 T utilizando etiquetas de giro de nitróxido específicas del sitio.
- Resonancia Paramagnética Electrónica (EPR, por sus siglas en inglés) para obtener información sobre la polaridad local y la movilidad.
- Probeando la dinámica del agua dentro de ~10 Å de las etiquetas de espín en la apomioglobina.
Principales resultados:
- El núcleo no polar del glóbulo fundido de apomioglobina está hidratado.
- El agua de hidratación en el glóbulo fundido exhibe una dinámica de traducción significativa (4-6 veces más lenta que el agua a granel).
- La apomioglobina nativa muestra dinámicas de hidratación heterogéneas, mientras que el estado desplegado tiene agua de difusión rápida.
Conclusiones:
- El ODNP específico del sitio es una herramienta poderosa para estudiar la dinámica de hidratación de proteínas.
- La dinámica de la hidratación de las proteínas es dependiente del plegamiento y varía según los diferentes estados de las proteínas.
- El agua proteica interna en glóbulos fundidos es dinámica, desafiando las suposiciones anteriores.
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