So the precursor inactive form of an enzyme is called a zymogen or sometimes a proenzyme. Now, in order to activate these zymogens, these pro enzymes, special molecules called proteases, which we spoke about previously, are basically used to cleave s special sites and that is what activates these polypeptides, these zymogens. And once activated, they can basically carry out their functionality until they are inhibited by some type of inhibitor, usually an irreversible inhibitor. And two examples of groups of enzymes which utilize this type of regulation method are digestive enzymes such as chimitrypsin trypsin, as well as pepsin, as well as all the different types of enzymes involved in a blood clotting cascade. And we'll discuss this in detail in future electra. So we have the zymogen that the cell produces, that's the inactive enzyme, the pro enzyme and then some type of protease cleaves the zymogen at some specific location.