Now, what about the specific activity? Well, the specific activity is simply the ratio of the enzyme activity to the total protein. So the units are unit per milligram are the units of the specific activity or micromol per minute per milligram, are the units of specific activity? Now, what does the specific activity actually tell us? Well, it tells us how pure or by how much more pure our sample is following that purification technique. And usually if the technique actually works this specific activity value has to increase as we'll see in just a moment.