Superoxide dismutase (SOD) are metalloenzymes that catalyze the dismutation of superoxide radical into hydrogen peroxide (H2O2) + molecular oxygen (O2) and consequently provide an important defense mechanism against superoxide radical toxicity (1). Oxidative stress dependent upon superoxide radical can account for a number of acute and chronic disease states, which include inflammation and ischemia-reperfusion (2,3). SOD protects murine peritoneal macrophages from apoptosis induces by adriamycine (4). Furthermore, over expression of SOD in fibrosarcome cells, protects against apoptosis and promotes cell differentiation (5).
- 100% Inhibition by Super Oxide Dismutase (SOD).
- Can detect low concentrations of SOD.
- Highly water-soluble formazan dye.
- Applications: Colorimetric detection.
Cell Technology’s SOD kit utilizes a water-soluble tetrazolium salt (WST-1) that produces a highly water-soluble formazan dye upon reduction with a superoxide anion (6). The rate of the reduction with O2.- is linearly related to the xanthine oxidase (XO) activity, and is inhibited by SOD, as shown in Figure 1. Therefore, the IC 50 (50% inhibition activity of SOD or SOD-like materials) can be determined by colorimetric method. Absorbance can be measured at 440nm.
Other direct and indirect methods have been developed but have issues with poor water solubility of the formazan dye and the interaction with the reduced form of xanthine oxidase. Cytochrome C is also commonly used for SOD activity detection, however, its reactivity with superoxide is too high to determine low levels of SOD activity.
Figure 1. Inhibition Curve Prepated Using SOD from Bovine Liver.