Physicochemical and biochemical properties of intestinal trypsin from sturgeon fish

Abstract This work aimed to determine the physicochemical and biochemical characterization of the intestinal trypsin from beluga (Huso huso) and sevruga (Acipenser stellatus), two highly valuable sturgeon species, by a series of assays. According to the results obtained from casein-zymogram and inhibitory activity staining method, indicating the existence of trypsin in the intestinal crude extract of both species, molecular weight of the enzyme was estimated to be 27.5 and 29.5 kDa in sevruga and beluga, respectively. Optimum pH and temperature of both trypsins were recorded at 8.5 and 55°C by BAPNA (a specific substrate), respectively. The stability of both trypsins was well preserved at pH from 6.0 to11.0 and temperatures of up to 50°C. TLCK and SBTI, two specific trypsin inhibitors, showed a significant inhibitory effect on the enzymatic activity of both trypsins (P < 0.05). The enzyme activity was significantly increased in the presence of Ca+ 2 and surfactants and decreased by oxidizing agents, Cu+ 2, Zn+ 2 and Co+ 2 (P < 0.05). However, univalent ions Na+and K+ did not show any significant effect on the activity of both trypsins (P > 0.05). Therefore, the results of our study can contribute to the clear understanding of the intestinal trypsin activity in beluga and sevruga under evaluated experimental conditions.