ABSTRACT
The inhibitor removes both forms of the enzymes equally from the reaction pathway and leaves a portion in a dead-end complex. Thus, even enzymes that catalyze near-equilibrium reactions in cells are irreversible in kinetic analysis. Classical cases of irreversible inhibition are the covalent modification of enzymes by the nerve gas isopropyl fluorophosphate and the acetylation of prostaglandin synthase by acetylsalicylic acid. However, in the case of pathway-reversible steps, there is a small cycle, often just two enzymes, that form a modified enzyme and return it to its original form. The compound aminooxyacetate is commonly used as a transaminase inhibitor because of its ability to form a Schiff base with pyridoxal phosphate, the bound cofactor in transaminase enzymes. While the specificity of enzyme inhibitors is in some ways a subjective determination, there are many compounds that are broader in their action, acting across different classes of enzymes. Kinetically, transporters are the equivalent of enzymes.
