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La unión de N2O en un grupo de cobre y azufre [4Cu:2S] en la óxido nitroso reductasa
Anja Pomowski1, Walter G Zumft, Peter M H Kroneck
1Lehrstuhl für Biochemie, Institut für organische Chemie und Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany.
Nature
|August 16, 2011
Resumen
Los investigadores revelaron la estructura de la reductasa de óxido nitroso (N2OR) con sustrato unido, aclarando su papel en la desnitrificación. Este hallazgo ilumina cómo las metalloenzimas activan pequeñas moléculas para la catálisis.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Química del medio ambiente Química del medio ambiente
- Biología Estructural Biología estructural.
Sus antecedentes:
- El óxido nitroso (N2O) es un potente gas de efecto invernadero con propiedades que agotan la capa de ozono.
- La desnitrificación bacteriana reduce el N2O a N2 a través de la reductasa de óxido nitroso dependiente del cobre (N2OR).
- Las estructuras N2OR anteriores carecían de información vinculada al sustrato, dejando su mecanismo incierto.
Objetivo del estudio:
- Para determinar la estructura de la reductasa activa de óxido nitroso (N2OR) con sustrato unido.
- Para dilucidar el mecanismo de reducción de N2O y activación por N2OR.
- Proporcionar información sobre la catálisis de la metalloenzima para la activación de moléculas pequeñas.
Principales métodos:
- Cristalografía de rayos X del N2OR púrpura obtenido de Pseudomonas stutzeri.
- Manipulación de enzimas bajo condiciones estrictamente anaerobias.
- Cristalización con N2O para capturar el estado ligado al sustrato.
Principales resultados:
- El sitio activo Cu(Z) de N2OR tiene una estequiometría de [4Cu:2S].
- Se observó que el óxido nitroso (N2O) se unía lateralmente al sitio Cu(Z), cerca del centro Cu(A).
- Se identificó una vía directa de transferencia de electrones de Cu(A) al sustrato N2O activado.
Conclusiones:
- La estructura revela la activación de N2O a través de la unión lateral en un bolsillo específico del grupo [4Cu:2S].
- Los hallazgos concilian los datos bioquímicos anteriores y proponen un mecanismo catalítico que involucra a ambos centros metálicos.
- Este trabajo proporciona la primera observación directa de N2O unido a su reductasa, avanzando la comprensión de las metalloenzimas.
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