Influence of various concentrations of phenol and its derivatives on the activity of fish intestinal peptidases

The effects of phenol and its derivatives (4-chlorophenol, 4-nirophenol and 2,4-dinitrophenol) on the activity of peptidases in five species of fish differing in feeding modes have been studied. The power of the effects depends on the fish species and localization of the enzyme (mucosa or chyme). As a rule, in the in vitro conditions the phenols in concentrations of 0.06?0.5 μM/L considerably decreases activities of the intestinal peptidases in bream; silver bream; and, especially, in pike. In some cases, phenol and its derivatives induce an inconsiderable increase in peptidase activities. In zander and perch, in fact, no changes in the enzymatic activity under impact of phenols are observed. It is suggested that the effect of phenol and its derivatives depends to a high extent on the species specificity of peptidases: in the fish of fam. Percidae, the enzymes are relatively tolerant; in fam. Cyprinidae and Esocidae, they are sensitive to the studied toxicants.