Probably involved in the metabolism of xenobiotics and of natural substrates. Hydrolyzes medium-chain monoalkyl phthalate esters. Inhibited by diethylpyrocarbonate, p-chloromercuribenzoate, Hg(2+) and Cu(2+). Not inhibited by the chelating reagents EDTA, 2,2'-dipyridyl, 1,10-phenanthroline, 8-hydroxyquinoline and tiron. Exhibits a smaller absorbance peak at 290 nm and a minimum at 250 nm. No significant absorption in the visible spectrum. Optimum pH is 7.5 with monobutyl phthalate as substrate. Retains 50% of maximum activity between pH 6.5 and pH 7.8. Optimum temperature is 40 degrees Celsius with monobutyl phthalate as substrate. Exists in two forms, E1 and E2. E2 is probably produced by modification of E1.