Superoxide synthase and dismutase activity of plasma membranes from maize roots |
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Authors: | Vuletić M Hadzi-Tasković Sukalović V Vucinić Z |
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Institution: | (1) Maize Research Institute, Belgrade, YU;(2) Center for Multidisciplinary Studies, Belgrade University, Belgrade, YU |
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Abstract: | Summary. Superoxide synthase and superoxide dismutase activity have been monitored in isolated maize (Zea mays) root plasma membranes spectrophotometrically by determination of nitro-blue tetrazolium and cytochrome c reduction, respectively. Superoxide production was induced by NADH and NADPH, with similar kinetics and approaching saturation
at 0.06 mM in the case of NADPH and 0.1 mM in the case of NADH, with rates of 18.6 ± 5.0 and 21.8 ± 7.2 nmol/min · mg of protein,
respectively. These activities exhibited a broad pH optimum between pH 6.5 and 7.5. Diphenylene iodonium inhibited about 25%
(10 μM DPI) and 40% (100 μM DPI) of this activity, imidazole inhibited about 20%, while KCN, a peroxidase inhibitor, did not
show any significant inhibition. Superoxide-dismutating activity was shown to occur in the same isolates and depended on the
quantity of plasma membrane protein present. Growth of plants on salicylic acid prior to membrane isolation induced a rise
in the activity of both of the enzymes by 20–35%, suggesting their coordinated action.
Received May 15, 2002; accepted September 30, 2002; published online May 21, 2003
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Keywords: | : Plasma membrane Redox system Salicylic acid Superoxide dismutase Superoxide synthase Zea mays |
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