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Una nueva luz sobre la unión de NO en las proteínas de Fe (III) hemo a partir de la espectroscopia Raman de
Alexandra V Soldatova1, Mohammed Ibrahim, John S Olson
1Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195, USA.
Journal of the American Chemical Society
|March 12, 2010
Resumen
La espectroscopia Raman de resonancia revela cómo la polaridad distal del bolsillo hemo afecta los enlaces de hierro-nitrosilo (Fe-NO) en la mioglobina. La polaridad alterada influye en la fuerza de enlace del NO, impactando los procesos biológicos de óxido nítrico (NO).
Área de la Ciencia:
- Química biofísica y bioquímica.
- La espectroscopia es una técnica de espectroscopia.
- Química computacional es la química computacional.
Sus antecedentes:
- Se estudiaron variantes de mioglobina con bolsas de hemo distales modificadas.
- Los aductos de hierro-nitrosilo (Fe-NO) son cruciales en las vías biológicas del óxido nítrico (NO).
- Comprender las interacciones Fe-NO proporciona información sobre el metabolismo del NO.
Objetivo del estudio:
- Para investigar la relación entre la polaridad del bolsillo hemo y las características de enlace Fe-NO.
- Explorar el papel de los sustituyentes distales de histidina y hemo en las frecuencias de estiramiento de Fe-NO.
- Para dilucidar los mecanismos que influyen en la flexión de Fe-NO y su correlación con las fuerzas de enlace.
Principales métodos:
- Espectroscopia Raman (RR) de resonancia visible y ultravioleta de las variantes de mioglobina.
- Modelado de la Teoría Funcional de la Densidad (DFT, por sus siglas en inglés) de los adductos Fe (III) -NO.
- Análisis de las frecuencias de estiramiento para los enlaces Fe (III) -NO (nu (FeN)) y N-O (nu (NO)).
Principales resultados:
- Se observó una correlación negativa entre el nu ((FeN) y el nu ((NO), lo que indica un backbonding.
- La pérdida de histidina distal desplazó la correlación, fortaleciendo el enlace N-O.
- Los sustituyentes de hemo que extraen electrones indujeron la flexión de Fe-N-O, lo que condujo a una correlación positiva.
Conclusiones:
- La polaridad del bolsillo hemo y la accesibilidad a la base de Lewis influyen significativamente en la dinámica de los enlaces Fe-NO.
- La espectroscopia RR y el modelado DFT informan efectivamente sobre el entorno del bolsillo heme.
- Los hallazgos tienen implicaciones para la comprensión de la unión al óxido nítrico (NO), la nitrosilación y la reducción en los sistemas biológicos.
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