Caracterização da atividade tríptica do copépodo harpacticoida Tisbe biminiensis

Abstract

Tisbe biminiensis is a potential live prey for many species of aquatic animals since its nutritional value is better than those found in other feed organisms commonly used in crustacean and fish larvivultures. Live food seems to be a source of exogenous enzymes which eases food digestion of fish and crustacean early life stages. The aim of this work was to study alkaline proteases from the harpacticoida copepod Tisbe biminiensis by evaluating the effects of pH, temperature and specific inhibitors on the proteolytic activity. Proteases were also studied by SDS-PAGE and zymograms. Crude extract from T. biminiensis showed a total proteolytic activity of 0.39 mU/mg of protein and tryptic activity of 2.33 mU/mg. Optima pH and temperature were 9.0 and 55oC, respectively. The enzymes were thermostable at temperature ranging from 25 to 50oC. The enzymatic activity was strongly inhibited by the trypsin specific inhibitors TLCK (100%), SBTI (100%) and benzamidine (91%).However, EDTA, PMSF and b mercaptoethanol caused only a slight inhibition (35, 35 and 7%, respectively). The results show that alkaline proteases are present on crude extract of Tisbe biminiensis. The highest effects of trypsin inhibitors on enzyme activity suggest that this enzyme plays an important role in protein digestion. T. biminiensis is an important source of live prey to fish and crustacean larvae in nature and partially replace others live food commonly used in aquaculture because they contribute with both exogenous enzymes for the digestion processes and other nutrients required during development of aquatic animals and contribute to development of aquaculture.