Which condition characterizes irreversible inhibition of enzyme function?

Irreversible inhibition of enzyme function is characterized by the binding of an inhibitor to the enzyme in a manner that permanently disables it. This often involves covalent modification of the enzyme's active site, such as the formation of covalent bonds between the enzyme and the inhibitor. Once this bond is formed, the enzyme cannot return to its active state regardless of conditions such as dilution or changes in temperature.

The nature of irreversible inhibition means that the enzyme's activity cannot be restored simply by removing the inhibitor, which distinguishes it from reversible inhibition, where the inhibitor binds non-covalently and can be displaced from the enzyme.

In contrast, the other conditions listed do not accurately reflect the mechanisms or characteristics of irreversible inhibition. For instance, dilution typically affects reversible inhibitors by reducing their effective concentration without altering the enzyme's structure, while extreme temperatures may affect enzyme function broadly but are not specifically linked to irreversible inhibition. Similarly, rapid synthesis of new enzymes might compensate in some scenarios but does not define irreversible inhibition itself; the key characteristic lies in the permanent nature of the inhibitor's effect on the enzyme.