Glutathione S-transferase in aquatic macro-invertebrates and its interaction with different organic micropollutants.

In higher organisms, glutathione S-transferase (GST) plays a key role in the detoxification of a large number of xenobiotics. In the present work the presence of GST in aquatic macro-invertebrates and its possible significance as a detoxification mechanism of organic micropollutants in the aquatic environment is investigated. So far, GST has been found in 20 macro-invertebrates (in adults as well as in larvae) and in insects as well as in other animal groups. The GST activities were relatively high, ranging from 10 to 600% of the activity found in rat liver. The interaction of quinones, o-chloranil and chlorophenoxyalkyl acids with the GST activity, in extracts from three different macro-invertebrates, revealed an inhibition which was quite similar to that previously found for rat liver GST. In Tubifex tubifex extracts at least three different GST isoenzymes could be demonstrated. These partially purified isoenzymes were used for the kinetic analysis of GST inhibition by 2,4-dichlorophenoxyalkyl acid and 1,4-benzoquinone, using Lineweaver--Burk plots. The same kinetic patterns were observed as for rat liver GST. The results demonstrate that the interactions of the compounds investigated with aquatic macro-invertebrate and with rat liver GST are in very good agreement. It is concluded that macro-invertebrate GST can play a key role in the detoxification of organic micropollutants in the aquatic environment.