抄録
Mammalian tissues or cells produce significant amounts of so called active oxygen species such as O-2, H2O2, ·OH, and 1O2 under certain physiologic and pathologic conditions. ClO- and lipid peroxides are sometimes included in the same category. In polymorphonuclear leukocytes, an NADPH oxidase system present in the plasma membrane converts molecular oxygen (O2) stoichiometrically into superoxide anion (O-2), which dismutates into hydrogen peroxide (H2O2) . Hydroxyl radical (·OH) and the rest of active oxygen species are produced from the two oxygen compounds either enzymatically or nonenzymatically. Recently, in vivo production of the active oxygen species was successfully demonstrated by detecting the oxyradical-dependent chemiluminescence from granulocytes sticking to venular endothelium in rat mesenteric microvascular bed (Suematsu, M. et al.: J. Biochem. 106: 350-355, 1989) . A similar but different NADPH oxidase system which produced O-2 from O2 was also demonstrated in the plasma membrane fraction from porcine thyroid cells (Nakamura, Y. et al.: J. Biol. Chem. 264: 4759-4761, 1989) . Then our present knowledge on the constitution and properties of the NADPH oxidase system in polymorphonuclear leukocytes has been reviewed and discussed with special reference to cytochrome b558, flavin-containing proteins and so called cytosolic factors.
