And so, if we mix this active side, so an enzyme that contains an active side with a serene, then this diesopropyl. Phosphorfluoridate will essentially form a covalent bond between this phosphor and this oxygen and that will kick off the f, the fluoride and also that H to form the following Covalent modification. And so these are two examples of group specific irreversible inhibitors. Now let's move on to the second type of category known as substrate analogs or more or more commonly affinity labels. So the thing about these affinity labels is the structure of that particular irreversible inhibitor actually resembles the structure of the natural substrate that binds into the active side of that enzyme. So these irreversible inhibitors are molecules that resemble substrates and this allows them to actually fit into the active side of that enzyme.