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Los péptidos cortos a base de alanina pueden formar hélices 3(10) y no alfa-hélices en solución acuosa
S M Miick1, G V Martinez, W R Fiori
1Department of Chemistry and Biochemistry, University of California, Santa Cruz 95064.
Nature
|October 15, 1992
Resumen
Los péptidos de alanina cortos pueden formar hélices alfa, pero distinguir entre las hélices alfa y las hélices 3(10) es un desafío. Nuevas técnicas de etiquetado de espín revelan que estos péptidos probablemente adoptan una estructura helicoidal de 3 10 en solución.
Área de la Ciencia:
- Química biofísica es la química biofísica.
- Biología estructural Biología estructural.
- La ciencia del péptido es la ciencia del péptido.
Sus antecedentes:
- Se cree que los péptidos cortos de alanina (16-17 residuos) forman alfa-hélices en solución acuosa.
- Los métodos espectroscópicos estándar como el dicroísmo circular (CD) y la resonancia magnética nuclear (RMN) no pueden diferenciar entre las hélices alfa y las hélices 3 ((10)).
- La hélice 3(10) implica un enlace de hidrógeno residual de i a i+3, distinto del enlace de i a i+4 en las hélices alfa.
Objetivo del estudio:
- Desarrollar y aplicar nuevos métodos para distinguir entre las estructuras alfa-helicas y 3(10) -helicas en péptidos cortos de alanina.
- Investigar las preferencias de estructura secundaria de los péptidos basados en alanina utilizando técnicas espectroscópicas avanzadas.
Principales métodos:
- Diseño y síntesis de análogos peptídicos de alanina con etiqueta de espín simple y doble.
- Incorporación de etiquetas de espín de nitróxido a través de residuos de cisteína.
- Análisis utilizando dicroísmo circular (CD), espectroscopia de infrarrojos con transformación de Fourier (FTIR) y espectroscopia de resonancia de espín de electrones (ESR).
Principales resultados:
- Las frecuencias de la banda FTIR amida I' difieren significativamente de las típicas de las hélices alfa.
- Los espectros de ESR de péptidos doblemente etiquetados indicaron clasificaciones de distancia de la cadena lateral inconsistentes con una conformación helical alfa.
- Los datos experimentales sugieren fuertemente una estructura helicoidal de 3...10) hélices.
Conclusiones:
- El estudio distingue con éxito entre las estructuras alfa-helicas y 3(10) -helicas en los péptidos cortos de alanina.
- El etiquetado de espín combinado con múltiples métodos espectroscópicos proporciona un enfoque poderoso para la determinación de la estructura de los péptidos.
- Los hallazgos indican que los péptidos de alanina cortos adoptan predominantemente una conformación helicoidal de 3 10 en solución.
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