reactivator

A reactivator is an agent that restores the activity of a system that has become inactivated or inhibited. The term is used across disciplines, from chemistry and materials science to biochemistry and medicine.

In chemical catalysis, reactivators are substances or procedures that remove poisons or restore active sites on catalysts. Deactivation can occur by poisoning, fouling, or sintering; reactivation methods include regeneration by burning, solvent washing, chemical treatment, or oxidation/reduction cycles that re-expose active sites. In sorbents and adsorbents, reactivation may involve thermal treatment to remove adsorbates.

In biochemistry and pharmacology, reactivators are compounds that reverse inhibition of enzymes. A well-known class are oximes that reactivate acetylcholinesterase after inhibition by organophosphates. Pralidoxime (2-PAM) and related agents, such as obidoxime, are used clinically as antidotes in organophosphate poisoning. Other enzymes can be reactivated by reducing agents or specific antidotes depending on the inhibition mechanism.

Limitations and timing are critical: reactivation depends on the inhibitor's age, the extent of modification, and the stability of the system. Some inhibitors form irreversible bonds, making reactivation ineffective. The term also appears in research contexts for restoring activity of denatured proteins or signaling components, though such use is more specialized.

Etymology: from re- (again) and activator, indicating restoration of function. See also reactivation in pharmacology and catalysis.