Please refer to attached aaaaapdf.

Thanks for your response. But the calculation is not clearly mentioned in this article. Further explanation of this calculation will be helpful for me.

Just check in Sigma Catalog under catalase. It tells you regarding one unit definition. Also the PDF I snt clearly tells:

Catalase activity was measured spectrophotometrically 1181 at

25 C in a Shimadzu UV 160 A spectrophotometer in a system

(total volume 1.0 ml) containing 50 mM potassium phosphate

buffer pH 7.0 and 10.5 mM H202. The reaction was initiated by

the addition of 75 ig of nucleus-free homogenate protein as

the source of the enzyme and was monitored by recording the

time taken for the decrease in the absorbance at 240 nm from

0.450 to 0.400. The activity is expressed as Sigma units [191.

Thus, one Sigma unit will decompose 1.0 imol of H202 per

mm at pH 7.0 at 25 C, while the H202 concentration falls from

10.3 to 9.2 mM (change in absorbance from 0.450 to 0.400).

You can use 2or 3 concentrations of our enzyme extracts and back calculate the concentration which will give O.D. change from 0.450 to 0.400

Again I am enclosing the PDF.

Thanks a lot. But your protocol and my protocol are different. And, so far, the calculation is not clear to me! I would like to request you to provide me a calculation of my protocol where the conc of catalase will be expressed as mM min-1 g-1 FW.

If Extinction coefficient= 40 M-1 cm-1 it means m mole/ml or O,D . for 1 micro mole /ml will be 0.04.

Your system is 3 ml in which 0.3 ml of extract is added and the O.D. change is 0.031.

Thus 0.031*3(total volume of the system/.004*0.3(volume of the extract added)= micro mole od H2O2 dismutated.

i.e 0.031*25= 0.775 microles H2O2 dismutated by 1.0 of extract.

Hopefully this is the answer you are looking for.

Thanks a lot for your answer. Now I get the solution of this problem. But I think you made one typo mistake. Instead of 0.004 it should be 0.04. So the final value will be 0.031*250=7.75.

Thanks again.

You are welcome. Glad to help.

Yes there was a typo mistake. However, the final answer is still 0.775. Re check your calculations.

All the best.