Superoxide H2O2 formation

R7. Root, R. K., and Metcalf, J. A., Hj02 release from human granulocytes during phagocytosis. Relationship to superoxide anion formation and cellular catabolism of H2O2 studies with normal and cytochalasin B-treated cells. J. Clin. Invest. 60, 1266-1279 (1977). 

The enzymes SOD, catalase and peroxidase are components of the antioxidative defense of the cell. As follows from the above, the CN-resistant respiration of propionic acid bacteria is responsible for most of the oxygen consumed by the cell with the attendant production of H2O2. The same type of respiration is the main source of superoxide radicals. It was shown (Vorobjeva and Kraeva, 1982) that NADH oxidation by membrane fractions of three strains, representing three different species, is accompanied by the formation of superoxide radicals (Table 3.11). Succinate oxidation, however, was not accompanied by a noticeable production of radicals. The highest rate of superoxide production was found in P, globosum, followed by P. coccoides and P. shermanii. Antimycin inhibited NADH oxidase activity in all the strains and simultaneously increased superoxide production by 32, 36 and 15%, respectively, in P. shermanii, P. globosum and P. coccoides. This showed that superoxide radical formation by propionic acid bacteria occurs in that part of the respiration chain that precedes the site of antimycin action. 

KMB. In both cases superoxide dismutase inhibited formation of ethylene but catalase did not. Nor did HjOi stimulate the formation of ethylene in the suspensions of granules leading the authors to propose that H2O2 was not an obligatory precursor of the oxidant. In other studies of PMNs stimulated with opsonized zymosan catalase did inhibit formation of ethylene as did superoxide dis-... 

In the DV of the parasite, free heme is rapidly converted to hematin, i.e., iron II is oxidized in iron III. During this process, electrons liberated promote the formation of reactive oxygen species (ROS) such as superoxide anion radicals and hydrogen peroxide [160], ROS can cause cellular damage. Hydrogen peroxide may also be used for the peroxidative degradation of heme. In this context, the influence of H2O2 on the redox behavior of FQ and implications for antimalarial activity was questioned. 

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