Assays of plasma membrane NADPH oxidase.

Publisher Summary Phagocytic cells, including neutrophils, eosinophils, and monocytes/macrophages, form part of the host defense system against infection. On binding to the target organism, there is an increase in oxygen consumption accompanied by the release of superoxide. This production of superoxide is catalyzed by a plasma membrane-bound enzyme: NADPH oxidase. Superoxide can undergo spontaneous or catalyzed dismutation to form hydrogen peroxide, or it can be converted to highly reactive oxidants, such as . OH or HOCl by a series of secondary reactions. The NADPH oxidase is normally dormant but can be activated by the addition of both soluble and particulate stimuli. The preferred electron donor is NADPH. The enzyme complex is composed of a membrane-bound b -type cytochrome together with at least three cytosolic components, which translocate to the membrane on activation. This complex is known to contain flavin adenine dinucleotide (FAD). Other nonphagocytic cells are also found to contain an NADPH oxidase-like enzyme. These include B lymphocytes, fibroblasts, mesangial cells, carotid body cells, and thyroid cells.