Catalase (CAT) is an enzyme in organism that can efficiently and specifically decompose hydrogen peroxide and is a binding enzyme with iron porphyrin as an auxiliary group. CAT clears hydrogen peroxide in the body and protects cells from the toxicity of H2O2. CAT can also oxidize certain cytotoxic substances, such as formaldehyde, formic acid, phenol and ethanol. According to the difference of catalytic center structure, CAT can be divided into two types, one is iron porphyrin structure, also known as iron porphyrin enzyme, the other contain manganese ion, also known as manganese catalase. CAT is common in breathing organisms. It is mainly found in chloroplasts, mitochondria, endoplasmic reticulum, liver and red blood cells of animals.

1)    Control tube: Add 1 mL of Reagent 1 into the 5 mL EP tubes.

Sample tube: Add a* mL of sample and 1 mL of Reagent 1 into the 5 mL EP tubes.

2)    Incubate at 37℃ for 5 min.

3)    Add 0.1 mL of Reagent 2 into each tube, mix fully and react at 37℃ for 1 min accurately.

4)    Sample tube: Add 1 mL of Reagent 3 application solution and 0.1 mL of Reagent 4, mix fully.

Control tube: Add 1 mL of Reagent 3 application solution, 0.1 mL of Reagent 4 and a* mL of sample, mix fully.

5)    Stand for 10 min at room temperature. Set to zero with double-distilled water and measure the OD values of each tube at 405 nm with 0.5 cm diameter cuvette.

Mix thoroughly, stand for 10 min at room temperature. Set to zero with double-distilled water and measure the OD values of each tube at 405 nm with 0.5 cm diameter cuvette.

Note: 1) If there are no obvious hemolysis and blood fat for serum (plasma) samples, or there is no high- fat in tissue homogenate samples, * can be replaced by double-distilled water for control tube. Control tubes only need 1-2 for each experiment.

2) For Serum or plasma samples, a* is 0.1 mL. For Tissue homogenates, a* is 0.05 mL.