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Atomic Scale Structural Studies of Macromolecular Assemblies by Solid-state Nuclear Magnetic Resonance Spectroscopy
Published on: September 17, 2017
(14) Acoplamiento cuadrupolar N de la estructura secundaria de nitrógeno amídico y péptido estudiado por
Jun Fukazawa1, Shin-Ichi Kato, Takuo Ozaki
1Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan.
Journal of the American Chemical Society
|March 12, 2010
Resumen
Este estudio revela que las hélices alfa exhiben acoplamientos cuádrupolares (14) N más grandes que las hojas beta en los péptidos. Este hallazgo ayuda a correlacionar la estructura secundaria del péptido con las interacciones nucleares cuádrupolares.
Área de la Ciencia:
- Espectroscopia de resonancia magnética nuclear de estado sólido (RMN) Espectroscopia de resonancia magnética nuclear de estado sólido (RMN)
- Química computacional es la química computacional.
- La biofísica es la biofísica.
Sus antecedentes:
- El acoplamiento nuclear cuadrupolar es sensible al entorno electrónico local alrededor de un núcleo.
- Las estructuras secundarias de péptidos, como las hélices alfa y las hojas beta, imponen restricciones estructurales distintas.
- Comprender la relación entre la estructura y los parámetros espectroscópicos es crucial para la caracterización molecular.
Objetivo del estudio:
- Para investigar la correlación entre la estructura secundaria del péptido (hélice alfa frente a la hoja beta) y la constante de acoplamiento cuadrupolar (14) N.
- Determinar si (14) el acoplamiento cuadrupolar N puede servir como un indicador confiable de la estructura secundaria en los polipéptidos.
- Para explorar la influencia de la composición de aminoácidos en esta relación estructura-espectroscopia.
Principales métodos:
- Se empleó espectroscopia de RMN de estado sólido (14) para medir los acoplamientos cuádrupolares (14) N.
- Se utilizó la observación indirecta de las resonancias de sobre tono (14) N bajo giro de ángulo mágico.
- Se realizaron cálculos ab initio (Gaussian03) en moléculas modelo para calcular (14) N acoplamientos cuádrupolares.
Principales resultados:
- Se observó una diferencia clara en el acoplamiento cuádrupolar (14) N entre las estructuras alfa-hélicas y las de hoja beta.
- Se encontró que los acoplamientos cuatrupolares para las hélices alfa eran consistentemente más grandes que los de las hojas beta en varios cientos de kHz.
- Esta diferencia fue independiente de los residuos específicos de aminoácidos estudiados (Ala, Val, Leu).
Conclusiones:
- El acoplamiento cuádrupolar (14) N es una sonda sensible de la estructura secundaria del péptido.
- Las estructuras alfa-hélices exhiben acoplamientos cuádrupolares (14) N significativamente más grandes en comparación con las estructuras de hojas beta.
- Este parámetro espectroscópico se puede utilizar para diferenciar entre las conformaciones alfa-hélicas y las de hoja beta en los polipéptidos.
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