Enzyme inhibitors reduce the efficiency of enzymes. There are two main classes of inhibitors:
Competitive inhibitors bind directly to the active site of an enzyme. They compete with the substrate for the active site.
Non-competitive inhibitors bind elsewhere on the enzyme and Change the shape of the active site so the substrate can no longer bind.
Inhibitors may also be reversible or irreversible.
Reversible inhibitors are commonly used by the body to slow down and control enzyme-catalysed reactions. These bind through hydrogen and ionic bonding.
Irreversible inhibitors bind covalently to the enzyme. Toxins often work this way.
It is easier to break ionic and hydrogen bonds compared to covalent bonds. Reversible inhibitors can be removed from enzymes while irreversible inhibitors are bound permanently.
Cyanide is a poisonous gas that acts as an irreversible inhibitor. It is produced by some plants, such as almonds, as a natural defence against predators.