Effects of Cd2+, Cu2+, Pb2+ and Zn2+ on activities of some digestive enzymes in carp (Cyprinus carpio L.)

The effects of haevy metals (Cd2+, Cu2+, Pb2+ and Zn2+) on activities of ca rp trypsin, alpha-chymotrypsin, carboxypeptidase A and lipase were studied. The enzymes were isolated from the gastrointestinal tract and the effects of metal ions were investigated during incubation for 5 min. The presence o f Cd2+ did not influence the activities of CPA and trypsin and 10-20 % inhi biton was observed with alpha-chymotrypsin and lipase. Cu2+ Only slightly i nfluenced the trypsin and lipase activities, whereas the alpha-chymotrypsin activity was decreased. All enzyme activities decreased at higher Zn2+ con centrations. The inhibition was most pronounced at alpha-chymotrypsin (more than 50%). With the exception of trypsin, Pb2+ inhibited the activities of the investigated enzymes.