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Investigando el modelo de enlace de hidrógeno de la desnaturalización de urea
Laura B Sagle1, Yanjie Zhang, Vladislav A Litosh
1Department of Chemistry, Texas A&M University, P.O. Box 30012, College Station, Texas 77843, USA.
Journal of the American Chemical Society
|June 17, 2009
Resumen
La urea facilita el colapso hidrofóbico en el poli (N-isopropilacrilamida) (PNIPAM) a través de la unión directa de hidrógeno, lo que contradice las teorías de desnaturalización de proteínas. Las ureas metiladas, sin embargo, aumentan el polímero.
Área de la Ciencia:
- La ciencia de los polímeros es la ciencia de los polímeros.
- Química biofísica y bioquímica.
- La desnaturalización de las proteínas.
Sus antecedentes:
- La urea es ampliamente aceptada como un denaturante que interrumpe la estructura de las proteínas a través de la unión directa.
- Comprender la interacción de la urea con los polímeros proporciona información sobre los mecanismos de desnaturalización de las proteínas.
Objetivo del estudio:
- Para investigar el mecanismo de unión directa de la urea con un polímero termorresponsivo, el poli (N-isopropilacrilamida) (PNIPAM).
- Para aclarar el papel del colapso hidrofóbico inducido por la urea y la unión de hidrógeno en las transiciones de fase de los polímeros.
Principales métodos:
- Mediciones termodinámicas del colapso hidrofóbico del polímero.
- Espectroscopia de la transformación de Fourier en infrarrojo (FTIR) para analizar el enlace de hidrógeno.
- Mediciones del radio de Stokes y cromatografía de filtración de gel para evaluar la conformación del polímero.
- Experimentos de transición de fase con varios derivados de la urea.
Principales resultados:
- La adición de urea disminuyó la temperatura crítica inferior de la solución (LCST) de PNIPAM, lo que indica un colapso hidrofóbico facilitado.
- Los datos de FTIR mostraron un enlace hidrógeno directo y cooperativo entre los grupos amídicos de urea y PNIPAM.
- Las mediciones del radio de Stokes confirmaron el enlace cruzado por debajo del LCST.
- La urea metilada aumentó el LCST y no mostró evidencia de unión directa al PNIPAM.
Conclusiones:
- El estudio proporciona evidencia en contra de un mecanismo directo de enlace de hidrógeno para la desnaturalización de proteínas inducida por urea.
- El efecto de la urea sobre el PNIPAM sugiere un mecanismo de interacción diferente al que se suponía anteriormente para la desnaturalización de proteínas.
- Los hallazgos destacan la importancia de la estructura del polímero y la sustitución de urea en la modulación de las vías de desnaturalización.
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