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 reduce
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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 activity of
SOD. The lighter the blue color of the reaction solution, the higher the activity of SOD.
Reagents and Equipment Required but Not Provided:
Spectrophotometer, table centrifuge, transferpettor, 1 mL glass cuvette, mortar/homogenizer, ice and
distilled water.
Operation steps:
I. Sample preparation:
1. Bacteria or cells: collecting bacteria or cells into the centrifuge tube, discard supernatant after
centrifugation. According to the proportion of bacteria or cells (104 cells): extraction solution volume (mL)
of 1:5-10 to extract. It is suggested that 5 million of bacteria or cells amount with 1mL of Extraction
reagent. Splitting the bacteria or cells 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: according to the proportion of tissue weight (g): extraction solution volume (mL) of 1:5-10 to
extract. It is suggested that 0.1 g of tissue with 1 mL of Extraction reagent and fully homogenized on ice
BC0170 -- page 1 / 4
