Purpose: The present study was aimed to determine the physicochemical and biochemical properties of trypsin from sevruga (Acipenser stellatus). Trypsin, as a serine protease found in the digestive system, is able to digest protein molecules by hydrolyzing long chains of amino acids into smaller pieces. Therefore, the enzyme activity has been widely used as a valuable indicator of digestive capacity in fish. Method: For determination of the physicochemical and biochemical properties of the enzyme, intestine from sevruga was obtained and cut into small pieces. After homogenizing in Tris–HCl buffer, the sample was centrifuged at 4°C and the supernatant was collected for further analysis including determination of the enzyme molecular weight, optimum temperature and thermostability, optimum pH and pH stability, and the effect of inhibitors, metal ions and surfactants & oxidizing agents on the activity of extracted enzyme. All experimental assessments were performed in triplicate, and data was analyzed by ANOVA by using SPSS software. Results: According to the results obtained from the study, optimum pH and temperature values for trypsin were recorded at 8.5 and 55 °C by BAPNA (a specific substrate), respectively. The stability of enzyme was well-preserved at pH values from 6.0 to 11.0 and temperatures up to 50 °C. Molecular weight of trypsin was estimated to be 27.5 kDa based on casein-zymogram and inhibitory activity staining methods. The enzyme activity was significantly inhibited by TLCK and SBTI and was significantly increased in the presence of Ca+2 and surfactants while oxidizing agents, Cu+2, Zn+2, and Co+2 decreased the enzyme activity (p < 0.05). However, univalent ions Na+ and K+ did not show any significant effect on the activity of the enzyme (p > 0.05). Conclusions: The results of this study showed that the properties of trypsin from sevruga was in agreement with data reported in bony fish and can contribute to the clear understanding of trypsin activity in
