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Efectos de la unión de As(III) en la estructura beta de la horquilla de pelo
Danny Ramadan1, Daniel J Cline, Shi Bai
1Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716-2522, USA.
Journal of the American Chemical Society
|February 22, 2007
Resumen
La unión del arsénico (III) a las proteínas cisteínas puede alterar las estructuras secundarias. Las ubicaciones específicas de cisteína en las horquillas beta mejoran o interrumpen el contenido de la hoja beta, influyendo en el arsénico.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Biología Estructural Biología estructural.
- Toxicología Toxicología.
Sus antecedentes:
- Los compuestos de arsénico (III) tienen efectos toxicológicos y farmacológicos significativos.
- Los mecanismos precisos de acción del arsénico y su impacto estructural en las proteínas, particularmente en los residuos de cisteinilo, no se comprenden completamente.
Objetivo del estudio:
- Para investigar cómo la unión del arsénico a las cisteínas afecta a la estructura secundaria de un modelo beta-hairpin.
- Determinar la influencia de la colocación de cisteína en la afinidad de unión al arsénico y las consecuencias estructurales.
Principales métodos:
- Síntesis de péptidos de una horquilla beta monomérica modelo con pares de cisteína diseñados.
- Caracterización mediante dicroísmo circular (CD), resonancia magnética nuclear (RMN), espectroscopia UV-vis y estudios de reacción rápida.
- Análisis de la unión del arsénico utilizando ácido monometilarsónico y p-succinylamidefenil arsenoxido (PSAO).
Principales resultados:
- Las cisteínas colocadas a través de la horquilla beta en la misma cara mejoraron la estructura de la hoja beta.
- Las cisteínas de cadena cruzada en caras opuestas aún se unen fuertemente al arsénico con un modesto aumento de la hoja beta.
- La unión de arsénico a cisteínas no opuestas o a lo largo de una sola hebra alteró la estructura de la hoja beta.
Conclusiones:
- Las consecuencias estructurales de la unión del arsénico a las proteínas dependen en gran medida de la disposición espacial de los residuos de cisteinilo.
- La unión al arsénico puede inducir cambios sustanciales en la estructura de proteínas secundarias locales, lo que afecta la función de los agentes bioactivos.
- Estos hallazgos proporcionan información sobre los mecanismos moleculares subyacentes a la toxicidad y farmacología del arsénico.
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