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SOD Assay Kit FAQs

What is the definition of a Unit?
One unit is defined as 50% inhibition of a colorimetric reaction between a reactive dye and superoxide anion. For example, if the O.D. of a sample that does not contain any SOD is 1.0, another sample that gives 0.5 O.D. is defined as having 1 unit of SOD activity. SOD activities determined using different dyes or methods are not comparable with each other.
Can I use a kinetic method to determine SOD activity?
Yes. Since the rate of the color development remains the same for up to 20 minutes, measure the slope for 5 minutes during this linear phase.
The sample has color. Can I still use this sample?
Probably. Diluting the sample will minimize the interference. Subtract the O.D. of a sample only control well from the O.D. of the test wells to cancel out the background color. However, if the SOD activity in the sample is very low, the activity may not be measurable.
How do I prepare more dilution buffer?
Dilution buffer is PBS. Please prepare the Dilution buffer with following concentrations; 137 mM NaCl, 2.7 mM KCl, 1.47 mM KH2PO4, 8.1 mM Na2HPO4, pH 7.4.
Can I determine Mn-SOD and Cu/Zn-SOD independently using this kit?
Yes. In order to measure Mn-SOD activity, it is necessary to block the Cu/Zn-SOD activity using potassium cyanide (KCN). Adding 1 mM KCN to samples can block Cu/Zn-SOD activity completely. To measure Cu/Zn-SOD activity, measure the total SOD activity with and without KCN, and then subtract the Mn-SOD activity from total SOD activity.
How long can I store the sample?
A sample stored in a freezer at -80C is stable for 1 month.