N-ACETYLTRANSFERASE ACTIVITY IN RAINBOW-TROUT LIVER AND IN-VITRO BIOTRANSFORMATION OF CHLORINATED ANILINES AND BENZENES IN FISH

1. N-acetyl transferase activity in liver homogenate of rainbow trout (Oncorhynchus mykiss) was studied. Enzyme activity depends on the conc entration of cofactor, has a broad pH and temperature optimum, is not linear with protein concentration within the whole range tested, and d oes not decrease upon storage at -70-degrees-C. 2. In vitro biotransfo rmation of several chlorinated anilines and benzenes was studied in li ver homogenates of rainbow trout and swordtail (Xiphophorus helleri). Several phase I and II products were detected in the simple in vitro b iotransformation assays using different cofactors NADPH-regenerating s ystem and acetyl-CoA, respectively. Acetylation of di-ortho substitute d anilines was not observed. 3. Apparent V(max) and K(m) values for th e acetylation of trichloroanilines have been determined using rainbow trout liver homogenate. The rate or extent of N-acetylation is related to the structure and properties of the chlorinated anilines. 4. Compa rison of the data for the two species showed that there are no apparen t qualitative differences in the in vitro fate of the chlorinated anil ines and benzenes studied. It is concluded that results obtained for t hese chemicals in the in vitro biotransformation assay can be extrapol ated between the taxonomic families of Salmonidae and Poeciliidae. 5. The in vitro and in vivo N-acetylation of the chlorinated anilines tur ned out to be strikingly similar. Therefore, simple in vitro systems m ay be of use in assessing the potential of chemicals to bioconcentrate .