Reactive nitrogen intermediates and antimicrobial activity: role of nitrite
SJ Klebanoff - Free Radical Biology and Medicine, 1993 - Elsevier
SJ Klebanoff
Free Radical Biology and Medicine, 1993•ElsevierThe reactive nitrogen intermediate (RNI) nitric oxide (NO⋅ is formed from l-arginine by an
NO⋅ synthase and, following secondary reactions yielding additional toxic intermediates,
nitrite (NO 12−) and nitrate formed. Nitrite, however, also has toxic properties. At acid pH,
nitrous acid (HNO 2) is bactericidal to Escherichia coli, in association with the loss of HNO
2/NO 2− and the uptake of oxygen, an effect which is increased by H 2 O 2. Under conditions
in which HNO 2/NO 2−±H 2 O 2 were ineffective, the further addition of peroxidase …
NO⋅ synthase and, following secondary reactions yielding additional toxic intermediates,
nitrite (NO 12−) and nitrate formed. Nitrite, however, also has toxic properties. At acid pH,
nitrous acid (HNO 2) is bactericidal to Escherichia coli, in association with the loss of HNO
2/NO 2− and the uptake of oxygen, an effect which is increased by H 2 O 2. Under conditions
in which HNO 2/NO 2−±H 2 O 2 were ineffective, the further addition of peroxidase …
Abstract
The reactive nitrogen intermediate (RNI) nitric oxide (NO⋅ is formed from l-arginine by an NO⋅ synthase and, following secondary reactions yielding additional toxic intermediates, nitrite (NO12−) and nitrate formed. Nitrite, however, also has toxic properties. At acid pH, nitrous acid (HNO2) is bactericidal to Escherichia coli, in association with the loss of HNO2/NO2− and the uptake of oxygen, an effect which is increased by H2O2. Under conditions in which HNO2/NO2− ± H2O2 were ineffective, the further addition of peroxidase (myeloperoxidase [MPO], eosinophil peroxidase, lactoperoxidase) or catalase resulted in bactericidal activity and the disappearance of HNO2/No2− also inhibited the bactericidal activity of MPO by the formation of a complex with MPO with a shift in the absorption spectrum, and by reaction with hypochlorous acid (HOCl) (the product of the chloride-supplemented MPO-H2O2 system), with loss of the bactericidal activity of HOCl and the disappearance of both HOCl and HNO2/NO2− from the reaction mixture. Thus, HNO2/NO2−, ra being solely an end product of RNI formation, may influence antimicroboal activity either by acting alone, with H2O2, or with H2O2 and peroxidase as a source of toxic agents, or by inhibiting the peroxidase-mediated antimicrobial systems.
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