The superoxide dismutase activity of iron complexes

The role of free radicals and radical processing systems in loss of desiccation tolerance in germinating maize (Zea mays L.)

“…Total glutathione and ascorbate were isolated and determined by the methods of, respectively, Sies & Akerboom (1984) and Foyer, Rowell & Walker (1983). Superoxide dismutase (EC 1.15.1.1) activity was determined using the xanthine-xanthine oxidase-^nitro blue tetrazolium system (Halliwell, 1975), quantified by the method of Giannopolitis & Ries (1977). Glutathione reductase (EC 1.6.4.2) activity was monitored as the oxidation of NADPH as described by Foster & Hess (1982).…”

Superoxide dismutase and catalase in the protection of the proton-donating systems of nitrogen fixation in the blue-green alga Anabaena cylindrica

“…Superoxide dismutase was assayed by three different methods: the xanthine/xanthine oxidase system (Halliwell, 1975), the riboflavin/methionine system (Beauchamp & Fridovich, 1971) and the K02 method (Henry et al, 1976). Nitro Blue Tetrazolium was used in each of the assay systems and the development of the blue colour caused by formazan production was followed at 560nm.…”

The superoxide dismutase activity of various photosynthetic organisms measured by a new and rapid assay technique

“…However, inhibition could also be attributed to prevention of the formation of O~ in these complex reaction mixtures (e.g. [11] ). Further, it is very difficult to study the effects of metabolites on superoxide dismutase activity, because of the possibility of interference with different stages of these assay systems [1 ].…”

“…In the K*O~ assay 5.850/ag of bovine erythrocuprein were required to give 50% inhibition of formazan production, However, only 0.135/ag of this enzyme was needed to reach 50% inhibition of the reduction of nitro-blue tetrazolium by a xanthinexanthine oxidase system at pH 7.8 [11] and 0.180/~g gave 50% inhibition in the riboflavin-methionine assay [7]. It is clear that the K÷O~ assay is less sensitive than the' others.…”

“…The calibration curves in riga were used to calculate the amount of superoxide dismutase in extracts of Spinacia, Chara and Nitella; the results are presented in table 1, in terms of the amount of erythrocuprein that would be required per ml of extract to give the same degree of inhibition. The extracts were also assayed by the xanthine-xanthine oxidase [11] and riboflavin-methionine [7] methods and similar calculations were made. Table 1 shows that the amounts of enzyme measured in the extracts by these three assays are quite similar, but that the xanthinexanthine oxidase assay gives consistently lower results than the others.…”