La firma vibratoria diagnóstica de la pentacoordinación en los carbonilos de hemo

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Douglas P Linder¹, Nathan J Silvernail, Alexander Barabanschikov

¹Department of Chemistry and Biochemistry, North Dakota State University , Fargo, North Dakota 58105, United States.

Journal of the American Chemical Society

|June 21, 2014

Resumen

Las nuevas firmas vibratorias de hemo-carbonilo revelan pentacoordinación. Los nuevos hallazgos sugieren que los carbonilos de la proteína hemo previamente estudiados son hexacoordinados, lo que afecta la comprensión de la función de las proteínas.

Área de la Ciencia:

La bioquímica es la bioquímica.
La biofísica es la biofísica.
Química computacional es la química computacional.

Sus antecedentes:

Los complejos hemo-carbonilo ofrecen información sobre las interacciones hemo-proteína.
La espectroscopia vibratoria es crucial para la caracterización de estos complejos.

Objetivo del estudio:

Establecer una firma vibratoria para la pentacoordinación verificada cristalográficamente en los complejos hemo-carbonilo.
Investigar las bases estructurales de la función de la proteína hemo.

Principales métodos:

Utilizó la espectroscopia de eco de espín de resonancia de neutrones (NRVS) en cristales únicos orientados de [Fe(OEP) ((CO) ].
Realizó cálculos de la Teoría Funcional de la Densidad (DFT) en varios modelos de hemicarbonilo.

Principales resultados:

NRVS reveló frecuencias más altas para el tramo Fe-C (ν(Fe-C)) que la curva FeCO (δ(FeCO)) en [Fe(OEP) ((CO) ], estableciendo una firma de pentacoordinación.
Los cálculos de DFT indicaron que este cruce de frecuencias ocurre cerca de donantes débiles de átomos trans O como el furan.

Conclusiones:

La firma vibratoria observada (ν ((Fe-C) > δ ((FeCO)) distingue a los carbonilos de hemo pentacoordinados.
Los datos existentes sobre los carbonilos de la proteína hemo (donde ν ((Fe-C) < δ ((FeCO)) sugieren que son hexacoordinados, no pentacoordinados como se suponía anteriormente.

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