NICOTINAMIDA ADENINA DINUCLEÓTIDO FOSTATO OXIDASA

 

                                                     

   Enzima de la membrana plasmática que cataliza la reducción univalente de oxígeno usando el NADPH como dador de electrones y formando anión superóxido. Esta enzima es un complejo proteico con una porción unida a la membrana celular (el citocromo b558), compuesto por los hemes gp91phox y p22phox, y una flavina-adenina dinucleótido. La porción membranosa constituye el núcleo catalítico que se activa cuando se une a los componentes citosólicos p40phox, p47phox y p67phox. Estos componentes están íntimamente asociados con la proteína G Rac2, que permite la translocación de aquellos hacia la membrana.

   <(F.): Nicotinamide adénine dinucléotide phosphate oxydase; NADPH oxidase: enzyme intervenant dans la destruction des bactéries. Elle fait défaut dans la granulomatose septique progressive.

   <(In.): NADPH oxidase: is an enzyme that catalyzes the production of superoxide from oxygen and NADPH. It is a complex enzyme consisting of two membrane-bound components and three components in the cytosol, plus rac 1 or rac 2. Activation of the oxidase involves the phosphorylation of one of the cytosolic components. Neutrophils and other phagocytic cells produce superoxide as part of their bactericidal mechanisms. Superoxide can react to form hydrogen peroxide, HOCl, and perhaps hydroxyl radical. Together, these oxygen-derived species participate in bacterial killing. The enzyme which catalyzes the production of superoxide is the NADPH oxidase or respiratory burst oxidase. The importance of the respiratory burst oxidase is illustrated by the inherited condition Chronic Granulomatous Disease (CGD) in which a component of the respiratory burst oxidase is absent or defective. Affected individuals suffer from recurrent, chronic and severe infections due to the inability of their neutrophils to kill microbes. Similar enzymes in other tissues produce superoxide and hydrogen peroxide, and in non-phagocytic tissues, these species may be involved as signal molecules regulating transcription, apoptosis and cell division. The Lambeth Lab studies the respiratory burst oxidase as a model for a signal transduction effector responses.

                                       

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