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Observación de la oligomerización del péptido β-amiloide por espectroscopia de RMN de salto de presión
C Ashley Barnes1, Angus J Robertson1, John M Louis1
1Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases , National Institutes of Health , Bethesda , Maryland 20892 , United States.
Journal of the American Chemical Society
|August 22, 2019
Resumen
La investigación de la enfermedad de Alzheimer revela que los oligómeros de amiloide-beta (Aβ) están altamente ordenados y son tóxicos. La RMN de salto de presión muestra que estos oligómeros tienen dinámicas estructurales distintas, lo que ayuda a comprender la toxicidad de Aβ.
Área de la Ciencia:
- La neurociencia
- La bioquímica
- Biología estructural
Sus antecedentes:
- Los cerebros de la enfermedad de Alzheimer muestran agregados de proteínas precursoras de amiloide (APP), específicamente péptidos beta-amiloide (Aβ).
- Las especies tóxicas exactas en la enfermedad de Alzheimer, las fibrillas u oligómeros, siguen siendo inciertas.
- Los oligómeros Aβ se forman rápidamente y suelen ser invisibles para la espectroscopia de RMN estándar.
Objetivo del estudio:
- Investigar las propiedades estructurales de los oligómeros Aβ utilizando RMN de salto de presión.
- Determinar si los oligómeros Aβ presentan estructuras ordenadas y dinámicas internas.
- Comprender el papel de los oligómeros Aβ en la patogénesis de la enfermedad de Alzheimer.
Principales métodos:
- Se utilizó la espectroscopia de RMN de salto de presión para resolver y estudiar rápidamente los oligómeros Aβ.
- Las señales de RMN monoméricas de Aβ monitoreadas después de la disociación inducida por presión de los oligómeros.
- Las tasas de relajación longitudinal (T1) y transversal analizadas para evaluar el orden estructural y la dinámica.
Principales resultados:
- Los oligómeros Aβ40 muestran un alto grado de orden estructural, evidenciado por una lenta relajación longitudinal N en regiones específicas (residuos 18-21 y 31-34).
- Los residuos N-terminales (1-10) de los oligómeros Aβ40 exhiben un movimiento interno significativo, indicado por tasas de relajación más rápidas.
- Las tasas de relajación transversal aumentaron bruscamente al inicio de la oligomerización, lo que sugiere cambios estructurales rápidos.
Conclusiones:
- Los oligómeros Aβ poseen una estructura definida y ordenada, lo que desafía la noción de que están completamente desordenados.
- La dinámica distinta observada en diferentes regiones de los oligómeros Aβ puede ser crucial para su toxicidad en la enfermedad de Alzheimer.
- La RMN de salto de presión es una técnica poderosa para estudiar especies transitorias e invisibles para la RMN como los oligómeros Aβ.
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