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La hélice se despliega en péptidos no disolvados
B S Kinnear1, M R Hartings, M F Jarrold
1Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, USA.
Journal of the American Chemical Society
|June 14, 2001
Resumen
El estudio examinó las conformaciones de péptidos utilizando la movilidad iónica. Un péptido siguió siendo un glóbulo, mientras que otro mostró una hélice alfa que se desplegó en una estructura intermedia de larga vida.
Área de la Ciencia:
- Física Química Física Química es la física de la química.
- Química biofísica y bioquímica.
- La dinámica molecular es la dinámica molecular.
Sus antecedentes:
- Comprender la estructura de los péptidos es crucial para la función biológica.
- Las conformaciones del péptido pueden ser influenciadas por la secuencia y el entorno.
- La movilidad iónica es una técnica poderosa para estudiar las estructuras de péptidos en fase gaseosa.
Objetivo del estudio:
- Para investigar las conformaciones dependientes de la temperatura de dos péptidos específicos: Ac-K (((AGG) ((5) + H ((+)) y Ac- ((AGG) ((5) K + H ((+)).
- Para caracterizar las vías de despliegue y la cinética de las estructuras de péptidos helicoidales.
- Para identificar posibles conformaciones intermedias durante el despliegue del péptido.
Principales métodos:
- Las mediciones de movilidad iónica se realizaron en un amplio rango de temperaturas (150-410 K).
- El análisis cinético del despliegue de la hélice se realizó utilizando constantes de velocidad.
- Se emplearon simulaciones de dinámica molecular para explorar paisajes conformacionales.
Principales resultados:
- El péptido Ac-K ((AGG) ((5) + H ((+)) mantuvo una conformación globular a través de todas las temperaturas probadas.
- El péptido Ac-{AGG}{5) K+H{+} exhibió tanto formas de hélice alfa como formas globulares a bajas temperaturas.
- El despliegue de la hélice alfa se produjo en una escala de tiempo de milisegundos, produciendo una energía de activación de 38.2 kJ / mol.
- Se observó una conformación intermedia de larga duración entre los estados de hélice y glóbulo.
Conclusiones:
- El péptido Ac-K ((AGG) ((5) + H ((+)) es conformacionalmente estable como una globula.
- El péptido Ac- ((AGG) ((5) K+H ((+) se somete a un despliegue inducido por la temperatura a partir de una hélice alfa.
- Es probable que una estructura intermedia distinta y estable facilite la transición de la hélice a la globula.
- Las simulaciones de dinámica molecular apoyan la existencia de este intermediario como una hélice parcialmente no retorcida.
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