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Química redox de transferencia de átomos de óxido de nitrógeno; Mecanismo de conversión de NO (g) a nitrito
Shabnam Hematian1, Isabell Kenkel2, Tatyana E Shubina2
1†Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21211, United States.
Journal of the American Chemical Society
|May 15, 2015
Resumen
Los complejos sintéticos de hemo-cobre oxidan eficientemente el óxido nítrico (NO) a nitrito, imitando procesos biológicos. Esta investigación detalla el mecanismo y los intermediarios involucrados en la regulación de NO.
Área de la Ciencia:
- Química bioorgánica Química bioorgánica.
- Química biofísica y bioquímica.
- Coordinación Química de la Coordinación
Sus antecedentes:
- El óxido nítrico (NO) es una molécula de señalización biológica crucial que requiere un estricto control de la concentración celular.
- La conversión oxidativa de NO a nitrito (NO2(-)) es un mecanismo regulador clave, mediado en parte por la citocromo c oxidasa.
- Comprender el metabolismo del NO es vital para varios procesos fisiológicos y patológicos.
Objetivo del estudio:
- Para investigar la oxidación eficiente del óxido nítrico gaseoso (NO) a nitrito (NO2(-)) utilizando construcciones sintéticas μ-oxo heme-Fe(III) -O-Cu(II) (L).
- Para dilucidar las vías mecanicistas e identificar especies intermedias involucradas en este proceso de oxidación del NO.
- Para comparar las estructuras y la reactividad de los nuevos complejos μ-oxo con los análogos existentes.
Principales métodos:
- Síntesis y caracterización de nuevos complejos μ-oxo hemo-cobre con ligandos variables (L).
- Investigaciones espectroscópicas (UV-Vis, EPR) y estudios cinéticos (flujo detenido a baja temperatura) para sondear los mecanismos de reacción.
- Cristalografía de rayos X para la determinación estructural y cálculos de la Teoría Funcional de la Densidad (DFT) para conocimientos mecanicistas.
Principales resultados:
- Los complejos sintéticos de μ-oxo catalizan de manera eficiente la oxidación de NO ((g) a nitrito (NO2 ((-)).
- La reacción procede mediante la adición secuencial de NO, formando un complejo ferroso heme-nitrosilo y un complejo cobre-nitrito.
- Se identificó y se caracterizó espectroscópicamente un intermediario clave, un adducto bis-NO [{NO}{porfirinato}Fe{II}{NO}{2}{-}{Cu}{II}{L}{+}.
Conclusiones:
- Los complejos sintéticos μ-oxo hemo-cobre imitan efectivamente la conversión de NO a nitrito observada en los sistemas biológicos.
- Se obtuvieron conocimientos mecanicistas detallados sobre la oxidación y el almacenamiento de NO, respaldados por datos experimentales y computacionales.
- Estos hallazgos contribuyen a la comprensión del papel del NO en la señalización biológica y las posibles estrategias terapéuticas.
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