The role of phosphotriesterases in the detoxication of organophosphorus compounds

The enzymes that hydrolyze organophosphorus compounds are called phosphotri esterases. The presence of phosphotriesterases has been described in a vari ety of tissues. The physiological role of these enzymes is not known, altho ugh a clear correlation exists between the levels of phosphotriesterases an d susceptibility of the species to the toxic effects of organophosphorus co mpounds. Thus, mammals that possess high levels of phosphotriesterases in s erum and liver are more tolerant to the toxic effects of these compounds th an birds and insects - these being species considered lacking of phosphotri esterases. Because most of these enzymes are not well characterized, they a re usually differentiated according to their different patterns of response to activators and/ or inhibitors. Phosphotriesterases usually depend of di valent cations and therefore EDTA usually inhibits them. A peculiar EDTA-re sistant phosphotriesterase has been described in serum albumin. The biotech nological and therapeutical applications of phosphotriesterases are current ly subject to study.