Irreversible Inhibition

In contrast to the above types of reversible inhibition, where the effects on the enzyme reaction depend on the concentration of an inhibitor (and its K_I), there are many examples of compounds that react chemically with residues in the enzyme active site.

In these cases, enzyme activity is destroyed. For example, the \"nerve gas\" Sarin reacts specifically with an active site Ser residue on the enzyme, acetylcholinesterase.

If acetlycholine cannot be hydrolyzed by this enzyme, nerve signals cannot be passed across the synapses of the nervous system. On exposure to this compound, death can result in minutes due to respiratory failure.