In organophosphate poisoning, what is the term for the process by which the phosphorylated acetylcholinesterase enzyme becomes permanently inactivated and can no longer be reactivated by oximes?

Explanation

## Enzyme Aging in Organophosphate Poisoning ### Definition of Aging **Key Point:** Aging is the spontaneous loss of an alkyl group from the phosphorylated enzyme complex, converting it from a reversible to an irreversible inhibitor. Once aging occurs, the enzyme cannot be reactivated. ### Timeline and Clinical Significance 1. **Initial binding:** Organophosphate phosphorylates AChE active site (reversible) 2. **Aging phase:** Alkyl group is lost from the phosphate moiety (hours to days, depending on the agent) 3. **After aging:** Enzyme is permanently inactivated; oximes (pralidoxime) cannot regenerate it ### Forensic and Clinical Implications - **Early intervention critical:** Oximes must be administered before aging occurs - **Timing varies by agent:** Some organophosphates age rapidly (minutes to hours), others slowly (days) - Parathion: ages in hours - Malathion: ages very slowly (days) - Sarin: ages in minutes - **Irreversibility:** Once aged, only new enzyme synthesis can restore function **High-Yield:** Aging is a time-dependent process that determines the window for effective oxime therapy. This is a frequently tested forensic toxicology concept. **Mnemonic:** **AGE** = **A**lkyl group **G**one = **E**nzyme permanently inactivated ### Why Other Terms Are Wrong - **Deamination:** Removal of amino groups; not relevant to organophosphate mechanism - **Phosphorylation:** The initial binding event, not the aging process - **Dealkylation:** The chemical process occurring during aging, but "aging" is the correct forensic/toxicology term