Let's suppose at this position here. And that creates the active form of the enzyme. So this piece is the active form and then this itself can be inhibited by using some type of irreversible inhibitor that binds onto some side found on that active form and that inhibits the activity of that enzyme. Now, the fourth type of mechanism of regulation is actually regulating the amount of the enzyme that is present in the cell. And usually, as we'll discuss eventually this type of regulation is monitored on the level of transcription. So if we control the amount of transcription that takes place on a particular gene of interest that codes for some type of enzyme, we can ultimately control how much of that enzyme is produced inside that cell and in turn control the activity and the functionality level of that particular enzyme.