A microtiter plate assay for superoxide dismutase using a water-soluble tetrazolium salt (WST-1).
A simple and reproducible microtiter plate assay for measuring superoxide dismutase (SOD) activity is described. Water-soluble tetrazolium, the sodium salt of 4-[3-(4iodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1,3-be nzene disulfonate, was used as a detector of superoxide radical generated by xanthine oxidase and hypoxanthine, in the presence of a range of concentrations of superoxide dismutase. A major advantage of the assay is that one reaction mixture is prepared and aliquotted into wells, avoiding pipetting errors and variable xanthine oxidase activity between samples. Inclusion of standardized SOD solution in each run enables inter-assay comparability without requiring a constant superoxide generation rate under all occasions. The assay is applicable for chloroform-ethanol red cell extracts as well as tissue homogenates without high-speed centrifugation. Fifty percent inhibition of formazan formation was achieved at 2.4+/-0.1 ng of Cu, ZnSOD per well with the coefficient of variation 4.2%.
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Free Radical Research Group, Department of Pathology, Christchurch School of Medicine, P.O. Box 4345, Christchurch, New Zealand.
Winterbourn
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D000818:Animals; D004912:Erythrocytes / Q000201:enzymology; D006801:Humans; D019271:Hypoxanthine / Q000032:analysis; D007202:Indicators and Reagents; D008099:Liver / Q000201:enzymology; D009206:Myocardium / Q000201:enzymology; D051381:Rats; D017208:Rats, Wistar; D013482:Superoxide Dismutase / Q000032:analysis*; D013481:Superoxides / Q000032:analysis; D013778:Tetrazolium Salts / Q000737:chemistry*; D014969:Xanthine Oxidase / Q000032:analysis
C110656:2-(4-iodophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium; D007202:Indicators and Reagents; D013778:Tetrazolium Salts; D013481:Superoxides; D019271:Hypoxanthine; D013482:Superoxide Dismutase; D014969:Xanthine Oxidase