Copper(II)-dependent hydrolysis of trichloronate by turkey serum albumin.

Trichloronate is a racemic organophosphonothioate insecticide that induced delayed neuropathic in hens and human. The avian are species with great susceptibility to organophosphorus poisoning due to their low levels of A-esterases. However, a significant copper-dependent A-esterase activity has been identified in chicken and turkey serum. This study aims at characterizing the trichloronate enantiomers hydrolysis by serum and albumin from chicken (CSA) and turkey (TSA) in the presence of copper by chiral chromatography. A significant Cu-dependent hydrolysis for both trichloronate enantiomers (38%) was observed in turkey serum and TSA (p < 0.05). The hydrolysis is stereoselective for (-)-trichloronate (p < 0.05). TSA incubation (200 μg) showed residual values of 56 μM and 20 μM of (+)-trichloronate and (-)-trichloronate, respectively; while the chicken serum and CSA presented a slight hydrolysis (1-7%) of both enantiomers. This copper-dependent hydrolysis and stereoselectivity of trichloronate by TSA was proportional to the incubation time. The increase of TSA in the assay (200-3000 μg) in the presence of 100 μM copper did not significantly increase the levels of hydrolysis and stereoselectivity, an opposite effect was observed for turkey serum (100-200 mL), which totally inhibited this copper-dependent activity of both isomers. The present study evidences an A-esterase activity of TSA on a thio form OP compound, which is stereoselective and activated by copper.