Superoxide dismutases (SODs) are metallo enzymes that catalyse the dismutation of the superoxide anion to molecular oxygen and hydrogen peroxide. Thus, it forms a crucial part of the cellular antioxidant defense mechanism. Bioquochem’s SOD Activity Assay Kit utilizes a tetrazolium salt for detection of superoxide radicals. Particularly, xantine oxidase and hypoxantine are the enzymes that generate these radicals (see scheme).
Excessive reactive oxygen species, especially superoxide anion (O2•−), play important roles in the pathogenesis of many cardiovascular diseases, including hypertension and atherosclerosis. Superoxide dismutases (SODs) are the major antioxidant defense systems against O2•−. There are three isoforms of SOD in mammals: the cytoplasmic Cu/ ZnSOD (SOD1), the mitochondrial MnSOD (SOD2), and the extracellular Cu/ZnSOD (SOD3). These enzymes require catalytic metal (Cu or Mn) for their activation.
SOD Activity Assay Kit
Bioquochem’s SOD Activity Assay Kit bases on the reduction of WST-1, that produces a water-soluble coloured formazan dye. The rate of the reduction with a superoxide anion linearly relates to the xanthine oxidase (XO) activity. By contrast, SOD inhibites this reaction. Therefore, the inhibition activity of SOD can be determined by a colorimetric method. Specifically, one unit of SOD corresponds to the amount of enzyme needed to exhibit 50% dismutation of the superoxide radical.
XO and SOD Antagonism in the Generation of Formazan Dye.
The conversion of xanthine and O2 to uric acid and H2O2 by XOD generates superoxide radicals. As a result, the superoxide anions reduce a tetrazolium salt (WST-1) to a colored formazan product (WST-1 formazan) that absorbs light. SOD scavenges superoxide anions, thereby reducing the rate of formazan dye formation.