You can measure the protein concentration separately using one of several methods, such as the Bradford assay or the BCA assay. For the pellet, you will have to redissolve it in something that is compatible with the protein assay.

Hi Adam,

I have a reading of spectrophotometer at 405nm of a solution and I wanted to indicate the percent protein expressed in the supernatant and pellet on the basis of absorbance measured at selective wavelength. can I use a standard for protein calculation of PNPP by using Beer-Lambert Law?

I think what you are asking is whether you can measure the concentration of the enzyme in the crude extract based on the result of the activity assay. You can do that as long as you know that there is only one enzyme in the extract that contributes significantly to the measured activity, and that there is nothing in the extract that inhibits the enzyme. If that is true, you can calibrate the measurement based on an activity assay using the purified enzyme under the same reaction conditions. It will be necessary to make sure that in both assays (crude extract and purified enzyme), you are measuring the initial rate of the reaction.

thanks, Adam appreciate your answer