Assay Principle:

The DetectX® Superoxide Dismutase (SOD) Activity Kit offers a reliable method for quantitatively measuring SOD activity in several sample types. These include serum, plasma, cells, tissue culture media, and erythrocytes. This activity assay, with a run time of 20 minutes, is designed for quick and efficient analysis. For comprehensive guidance, users should read the complete kit insert before conducting the assay. The kit includes a Superoxide Dismutase Standard to establish an accurate standard curve.

Protocol Summary:

• Place standards or diluted samples into the provided transparent microtiter plate.
• Add Substrate Preparation mixture and Xanthine Oxidase Preparation mixture to each well, ensuring thorough mixing.
• Incubate the mixture at room temperature for 20 minutes. This allows for the color-generating reaction between Xanthine Oxidase, oxygen, and the colorless substrate.
• After incubation, use a plate reader to detect the generated signal at 450nm and calculate SOD activity using the standard curve.

Background:

Superoxide dismutases (SODs) are key enzymes in the body’s antioxidant defense system, scavenging harmful oxygen species such as superoxide (O2-·), hydroxyl radical (·OH), and hydrogen peroxide (H2O2). These enzymes, including copper-zinc superoxide dismutase (Cu/ZnSOD), manganese superoxide dismutase (MnSOD), and extracellular superoxide dismutase (EC-SOD), are critical in controlling cellular ROS levels. Reduced SOD activity can lead to elevated superoxide levels, impacting NO availability and increasing peroxynitrite concentrations.

Cu/Zn SOD, a 32-kDa homodimer containing copper and zinc, is the primary intracellular SOD. MnSOD, found in mitochondria, is a manganese-containing 93-kDa homotetramer synthesized in the cytoplasm and transported to the mitochondrial matrix. Many organs highly express EC-SOD, the main extracellular SOD enzyme. Altered SOD activity levels are associated with several conditions, including Down Syndrome, diabetes, Alzheimer’s disease, rheumatoid arthritis, Parkinson’s disease, uremic anemia, atherosclerosis, certain cancers, and thyroid dysfunction. The DetectX® Superoxide Dismutase (SOD) Activity Kit is a useful tool for researchers studying oxidative stress, cellular defense mechanisms, and diseases related to altered antioxidant enzyme activity.