Effects of temperature,pH, and heavy metals (copper,zinc) upon proteinase activities in digestive tract mucosa of typical and facultative piscivorous fish

Species-specific differences and effects of natural (temperature, pH) and anthropogenic (zinc, copper) factors upon activities of casein-and hemoglobinlytic proteinases have been studied in the gut mucosa in pike (Esox lucius), zander (Stizostedion lucioperca), burbot (Lota lota) and perch (Perca fluviatilis). It is revealed that the intestine mucosa proteinase activities differ considerably from those ones in the fish stomach mucosa and that studied factors affect these activities to different extents. The stomach mucosa proteinases are most tolerant to the effects of studied factors, which is especially true for pike. The least tolerant are the intestine caseinlytic proteinases (except for the enzymes in perch). The effects of temperature, pH, and heavy metals depend on fish species, factors’ combinations (mono-factor, bi-factor, or multi-factor action) and on factor variability.