Organophosphorus compounds enzyme-inhibiting properties

Some general methods can also be adapted to the determination of individual organophosphorus compounds. For instance, the cholinesterase-inhibiting properties of methylparathion, dimethoate and their oxygen analogues were used for their determination a known amount of enzyme is incubated with the sample, then addition of a chromogenic agent such as p-nitrobenzenediazonium fluoroborate yields a... 

Coumarin insecticides usually contain the coumarin molecule with an 0,0-diethyl phosphate or 0,0-diethyl phosphothionate radical, e.g. Potasan, (0,0 diethyl-0-(4-methyl-7-coumaryl)phosphothionate) (111) Coumaphos, (0,0 diethyl-0-(3-chloro-4-methyl-7-coumaryl) phosphothionate (112) Haloxon, (0,0-diethyl-O-(3-chloro-4-methyl-7-coumaryl) phosphate (113). The mode of action of these compounds combines the toxic properties of coumarin moiety with the action of the organophosphorus compounds. The latter acts by inhibiting the esterase enzyme systems in the insects, particularly cholinesterase, probably by phosphorylation of the active site of the enzyme. 

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