Activity of digestive hydrolases in carp Cyprinus carpio with different mercury content in food

The concentration of mercury in muscles of experimental carp Cyprinus carpio whose diet contained high levels of mercury gradually increased and in 6 months became 5.4 times higher than in the control group. This increase was accompanied by a decrease in the activity of glycosidases in the intestinal mucosa, as a rule, and an increase in the activity of proteases. The observed effects were most pronounced in the optimum pH range of the enzymes. The maximum rates of the reactions catalyzed by proteinases in the fish of the experimental group were equal to or slightly higher than in the control throughout the experiment, whereas the Michaelis constant values, conversely, were much lower. The maximum rates of the reaction catalyzed by glycosidases decreased 2–3 months after the beginning of the experiment (by 14–21%), and the Michaelis constant values decreased almost throughout the experiment.