If you are more specific, there will be somebody who could address it. In general, you will need to do the basic biochemistry (add substrate and measure product) and calculate Vmax and Km.

First, you have to determine the enzyme activity i.e. U/ml.

Then you should estimate the protein concentration, i.e. mg/ml.

Now, you should divide the enzyme activity with the protein concentration and you will get U/mg which is basically specific activity, U/mg.