Has an unusual substrate specificity for synthetic organophosphate triesters and phosphorofluoridates. All of the phosphate triesters found to be substrates are synthetic compounds. The identity of any naturally occurring substrate for the enzyme is unknown. Has no detectable activity with phosphate monoesters or diesters and no activity as an esterase or protease. It catalyzes the hydrolysis of the insecticide paraoxon at a rate approaching the diffusion limit and thus appears to be optimally evolved for utilizing this synthetic substrate (By similarity). An aryl dialkyl phosphate + H2O = dialkyl phosphate + an aryl alcohol. Binds 2 Zn(2+) ions per subunit. Homodimer. Predicted to be exported by the Tat system. The position of the signal peptide cleavage has been experimentally proven. Belongs to the metallo-dependent hydrolases superfamily. Phosphotriesterase family.