Aspirin is another example of an irreversible covalent inactivator of prostaglandin-endoperoxide synthase, also called cyclooxygenase, or COX.
The DNA-polymerases is an important drug targets because of their critical role in replication. Deoxynucleotide-based inhibitors are recognized as substrates for the enzyme, and terminate strand extension because they lack the ribose hydroxyl necessary for ligation to the next nucleotide. In this sense, the inhibition is of irreversible types. Acyclovir, which targets herpes virus DNA-directed DNA polymerase, does produce irreversible enzyme inactivation in addition to nucleotide incorporation and strand termination.

Figure 3.13a: Vigabatrin-a suicide substrate of GABA.

Figure 3.13b: Vigabatrin-a suicide substrate of GABA-Mechanism of action.

Figure 3.13c: Vigabatrin-a suicide substrate of GABA-Mechanism of action of enzyme inactivation.