Organophosphate insecticides, AChE inhibitors

Fig. 12.6 Basic structures of organophosphate AChE inhibitors. X represents the leaving group, (a) Typical agricultural insecticides (b) typical chemical warfare agents.

Because suicide inhibitors bind to the active site, the can be used to find what amino acids are present there. Malathion and other organophosphates are suicide inhibitors of insect AChE, so are widely used as insecticides. 

Answer D. The symptoms of cholinergic excess seen in this child are indicative of exposure to insecticides such as the organophosphate parathion, which cause irreversible inhibition of acetylcholinesterase. Other symptoms may include CNS excitation and stimulation of the skeletal NMJ, ultimately leading to paralysis of respiratory musdes— DUMB-BELSS. In addition to symptomatic support, management of AChE inhibitor poisoning involves the use of atropine and 2-PAM. 

Atropine + pralidoxime (for irreversible AChE inhibitors AChE inhibitors—physostigmine, neostigmine, + pyridostigmine, organophosphates including insecticides such as malathion and parathion... 

Cholinesterase inhibitor (anti-cholinesterase, ChEI) is a chemical that prevents cholinesterases (ChEs) from breaking down. ACh, which consequently increases the level and duration of action of this neurotransmitter. ChEIs such as organophosphates (esters of phosphoric acid) and carbamates (esters of carbamic acid) - serve as insecticides, pesticides, warfare agents and drugs. 

The mode of action of the carbamate insecticides is similar to that of the organophosphates. As shown in Figure 7.15, the reaction yields a carbamylated AChE, followed by decarbamylation via hydrolysis. Carbamates also attack the CNS system, and the symptoms of intoxication are similar to those with the organophosphates. However, unlike the organophosphates, decarbamylation of acetylcholinesterase is rapid, typically in minutes, and therefore carbamate insecticides are regarded as reversible acetylcholinesterase inhibitors. 

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