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Analytical Techniques for Assaying Nitric Oxide Bioactivity
Published on: June 18, 2012
Evidencia física de la unión al sustrato en la prevención de la inactivación de la ciclooxigenasa bajo estrés
Ruba S Deeb1, Cynthia Cheung, Tal Nuriel
1Department of Pathology, Weill Cornell Medical College of Cornell University, 1300 York Avenue, New York, New York 10065, USA. rsdeeb@med.cornell.edu
Journal of the American Chemical Society
|March 4, 2010
Resumen
La unión al sustrato protege a la ciclooxigenasa-1 (COX-1) de la inactivación por las especies reactivas de nitrógeno. Este hallazgo revela un nuevo mecanismo de protección para la actividad de COX-1 durante el estrés oxidativo.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Enzimología Enzimología.
- Biología Molecular Biología Molecular
Sus antecedentes:
- Las enzimas ciclooxigenasa (COX) catalizan la biosíntesis de las prostaglandinas a través de distintos sitios activos.
- La regulación y la función de las enzimas COX no se comprenden completamente.
- El estrés oxidativo genera especies reactivas de nitrógeno que modifican las enzimas COX, alterando la producción de prostaglandinas.
Objetivo del estudio:
- Para investigar los mecanismos de protección de la ciclooxigenasa-1 (COX-1) contra la inactivación nitrativa.
- Determinar el papel de la ocupación del sustrato en la regulación de la COX-1 por las especies reactivas de nitrógeno.
Principales métodos:
- Mutagénesis dirigida al sitio para identificar los principales residuos de tirosina.
- Los ensayos de cinética enzimática miden la actividad de la COX-1.
- Espectrometría de masas para confirmar las modificaciones de las proteínas.
Principales resultados:
- COX-1 se somete a una nitratación selectiva en Tyr385, lo que lleva a la inactivación catalítica.
- La unión del sustrato al sitio activo de COX-1 impide la nitratación de Tyr385.
- La nitratación se redirige a otros residuos de tirosina cuando el sitio activo está ocupado por el sustrato, preservando la actividad de la enzima.
Conclusiones:
- La ocupación del sustrato es un factor crítico para proteger a COX-1 de la inactivación nitrativa.
- Este estudio descubre un nuevo mecanismo para la regulación y protección de COX-1 en condiciones fisiopatológicas que involucran estrés oxidativo.
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