Superoxide dismutase (SOD, EC 1.15.1.1) is widely found in animals, plants, microorganisms and
cultured cells. It catalyzes the superoxide anion to form H2O2 and O2. SOD is not only the superoxide
anion scavenging enzyme, but also the main H2O2 producing enzyme, which plays an important role in the
biological antioxidant system.
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Superoxide anion (O2 ) is produced by the xanthine and xanthine oxidase reaction system. O2 can
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reduce blue tetrazole to form blue formazan, which has absorbance in 560 nm. SOD can remove O2 and
inhibit the formation of methionine. The darker the blue color of the reaction solution, the lower the SOD
activity. The lighter the blue color of the reaction solution, the higher the activity of SOD.
Operation steps:
I. Sample preparation:
1. Bacteria or cells: collecting bacteria or cells into the centrifuge tube, discard supernatant after
centrifugation. It is suggested that 5 million of bacteria or cell amount with 1 mL of Extraction reagent.
Splitting the bacteria or cell with ultrasonication (placed on ice, ultrasonic power 200W or 20%, working
time 3s, interval 10s, repeat for 30 times). Centrifuge at 8000 g for 10 minutes at 4℃ to remove insoluble
materials, and take the supernatant on ice before testing.
2. Tissue: it is suggested that 0.1 g of tissue with 1 mL of Extraction reagent and fully homogenized on
ice bath. Centrifuge at 8000 g for 10 minutes at 4℃ to remove insoluble materials, and take the
supernatant on ice before testing.
BC0175 -- page 1 / 4
