Question

As an enzyme is purified, both the amount of total protien and the activity of the purified protien go down. Why, then does the specific activity of the purified protein go up?

Answer 1

In purification process

undesired proteins are purified away so the amount of total protien go down

total activity is actual number of acivity units (U) recovered is go down because protein is lost in various steps of purification and denatured during manipulations.

specific activity is the ratio activity units to amount of protein (U/mg) which should increase during the purification process because desired protein activity remains higher and higher in each purification step hence the specific activty of the purified protein go up.