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Construction and Systematical Symmetric Studies of a Series of Supramolecular Clusters with Binary or Ternary Ammonium Triphenylacetates
Published on: February 15, 2016
Efectos de la unión de As(III) en la estructura helical alfa
Daniel J Cline1, Colin Thorpe, Joel P Schneider
1Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716-2522, USA.
Journal of the American Chemical Society
|March 6, 2003
Resumen
El arsénico (III) que se une a los residuos de cisteína en los péptidos modelo desestabiliza las estructuras alfa-hélices, alterando el plegamiento de las proteínas. Los arreglos específicos, como i, i+3, pueden eliminar las hélices, mientras que los arreglos i, i+4 las estabilizan.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Biología Estructural Biología estructural.
- Biología Química Biología química.
Sus antecedentes:
- El arsénico (III) tiene diversos efectos celulares, pero su impacto en la estructura de las proteínas no se comprende bien.
- Los residuos de cisteína son sitios de unión clave para el arsénico en los sistemas biológicos.
Objetivo del estudio:
- Para investigar las consecuencias estructurales de la unión del arsénico (III) a los péptidos alfa-hélicos.
- Determinar cómo la disposición y ubicación de los residuos de cisteína influyen en la unión al arsénico y en los cambios estructurales.
Principales métodos:
- Se utilizó la espectroscopia de dicroísmo circular (CD) para analizar la estructura secundaria del péptido.
- Se sintetizaron péptidos alfa helicoidales modelo con diferentes arreglos de residuos de cisteína (Cys).
- Se midieron las afinidades de unión y las constantes de tasa de asociación.
Principales resultados:
- El arsénico ((III) se une a las hélices desestabilizadas cuando los residuos de Cys se encuentran en posiciones centrales o C-terminales con arreglos i, i+1, i+2 o i+3.
- La unión de arsénico a los residuos de Cys en la posición i, i+3 eliminó la estructura helicoidal, formando un pliegue alternativo.
- La estabilización helicoidal se produjo para péptidos con i, i + 4 residuos de Cys, con energías de interacción medidas.
- La afinidad de unión de As(III) fue en gran medida insensible a la ubicación de Cys en helices moderadamente estables.
Conclusiones:
- La unión al arsénico modula significativamente la estructura secundaria alfa-helical.
- La disposición espacial de los residuos de cisteína dicta el resultado estructural de la unión del arsénico.
- Comprender estas interacciones es crucial para comprender los mecanismos celulares del arsénico.
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