LUCIGENIN AND LINOLEATE ENHANCED CHEMILUMINESCENT ASSAY FOR SUPEROXIDE-DISMUTASE ACTIVITY

The xanthine/xanthine oxidase dependent chemiluminescence was enhanced both by lucigenin and linoleate to create a sensitive, specific, and rapid chemiluminescent method for superoxide dismutase (SOD) activity determination. A pH optimum at around 10.0 was found both for the chem iluminescence and its inhibition by SOD. At this pH, a linear inhibiti on response to concentrations from 0.01 to 100 ng/ml of bovine Cu,Zn S OD could be established, with a 50% inhibitory concentration of 0.75 n g/ml. As little as 0.17 fmol of Cu,Zn SOD per test can be detected. Wi th a slightly lower sensitivity, the method is operative at pH 7.4, to o. Both Cu, Zn SOD and Mn SOD can be assayed. The rationale of the ass ay is in combining a superoxide-producing enzymatic system with linole ate amplification to enhance the sensitivity of the chemiluminescence to inhibition by SOD activity. Applicability of the method to biologic al samples was tested with a standard addition experiment.