Editing Parathion (section)

==Insecticidal activity==
Parathion acts on the enzyme [[acetylcholinesterase]] indirectly.  After an insect (or a human) ingests parathion, an [[oxidase]] replaces the double bonded sulfur with oxygen to give [[paraoxon]].<ref name = metcalf>{{cite book |last=Metcalf |first=R. L. |chapter=Insect Control |title=Ullmann's Encyclopedia of Industrial Chemistry |publisher=Wiley-VCH Verlag GmbH & Co. KGaA |location=New York |year=2002 |doi=10.1002/14356007.a14_263 |isbn=978-3527306732 }}</ref>

:{{chem2|(C2H5O)2P(S)OC6H4NO2 + 1/2 O2 → (C2H5O)2P(O)OC6H4NO2 + S}}

The phosphate ester is more reactive in organisms than the phosphorothiolate ester, as the phosphorus atoms become much more electropositive.<ref name = metcalf/>

Parathion {{visible anchor|Resistance|text=resistance}} is a special case of [[acetylcholinesterase inhibitor resistance]].