An irreversible inhibitor will bind to an enzyme so that no other enzyme-substrate complexes can form. It will bind to the enzyme using a covalent bond at the active site which therefore makes the enzyme denatured. An example of an irreversible inhibitor is diisopropyl fluorophosphate which is present in nerve gas. It binds to the enzyme and stops nerve impulses being transmitted. An example of where we use irreversible inhibitors in medicine is penicillin. Penicillin works by inhibiting the activity of the enzyme responsible for the creation of the bacterial cell wall. This means that water can enter the bacterial cell, causing it to swell, burst and die termed lysis.