Dear all,I am stuck in calculation of CAT and APx activities in plants.I used SPECIFIC ENZYMATIC ACTIVITY formula.For CAT assay i used 100ul plant enzyme but for APx i used 40ul plant enzyme.
So if i want to compare both activity level in plants,then what will i do?I thought i have to multiply APX activity value till 100ul as in CAT.or some thing else.
Please guide
Hi there,
So the source of enzyme is the same but the volume engaged in the 2 assays are different. Then there is no problem as specific activity is actually related to the ratio (initial velocity measured) / (volume of enzyme used). Therefore the fact that different volumes have been used are included into the calculation (have a check in your formula, there has to be a volume of enzyme somewhere).
Specific activity is expressed as units of activity per mg of protein. So, measure the protein concentrations in your samples, calculate how many mg of protein were in each reaction, and divide the activity by the mg of protein. The different volumes of samples used become part of the calculation of mg. For example, if the protein concentration of the sample was 1.5 mg/ml (= 1.5 µg/µl) and you used 40 µl for the reaction, then the reaction contained 60 µg (= 0.06 mg) of protein.
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