FAQ: Catalase Activity Assay, Colorimetric

Q: Can this kit be used with samples from any species?

A: Yes, our Catalase Assays are not species specific and should work with any biological protein sample because they measure enzymatic activity rather than protein structure.


Q: Is it possible to test samples that have been stored frozen?

A: Two months at -80ºC generally the longest most antioxidant samples should be stored, but we recommend testing fresh samples wherever possible for the best results.


Q: My lysates were prepared in RIPA buffer. Can I use this assay? 

A: We have not tested our Colorimetric Catalase Assay with RIPA buffer, but we believe that it may be compatible. It is not recommended to use detergents such as SDS on samples that are being tested with an enzymatic assay, because it could affect protein integrity and therefore the enzymatic activity that is being tested.  For best results, we recommend preparing lysates by homogenizing or sonicating cells in PBS without the use of detergents.  If you want to use your lysates that are in RIPA buffer, it is recommended to run a buffer control alongside a lysate sample to determine any background signal that is resulting from the buffer alone.


Q: Is this compatible with plasma samples collected in EDTA?

A: EDTA will not interfere with this assay and it is fine to use plasma samples collected with EDTA instead of heparin or citrate.


Q: Can plasma samples be prepared without the centrifugal ultrafiltration tube?

A: We recommend using the centrifugal ultrafiltration tube when preparing plasma samples for use in the Colorimetric Catalase Activity Assay, because this will remove ascorbic acid and uric acid from the samples, which can interfere with the assay. 


Q: Do you have an assay to test for catalase inhibition?

A: We don’t have a catalase inhibition assay, but our Colorimetric Catalase Activity Assay can be used to detect a decrease in activity.  An option for you may be to treat your samples with an inhibitor and run the assay along with an untreated control sample.  If catalase activity is inhibited, you would expect a decreased catalase level compared to the control sample.


Q: How do I calculate my unknown values from the standard curve?

A: The best way to determine concentrations from a standard curve is to use a 4-parameter curve fitting program, but if you don’t have this software it can be done using Excel.  The trendline of the curve is a second order polynomial, so the easiest way to perform the calculation is to graph the OD values as the x-axis and the catalase standard concentrations as the y-axis (see figure 3 in the product manual).  The equation can then be solved by plugging in the unknown sample OD values for x and solving for y.