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The effect of metal ions, surfactant, oxidizing agents and enzyme inhibitors was considered on trypsin and chymotrypsin activity of the Caspian brown trout fry. The results showed K⁺ and Na⁺ didn’t significanly decrease trypsin and chymotrypsin activity (p>0.05). Ca²⁺ and Mg²⁺ significantly increased trypsin and chymotrypsin activity (p<0.05). Mn²⁺,Cu²⁺,Ba²⁺,Co²⁺,Zn²⁺,Fe²⁺ and Al³⁺ significantly decreased the activity of trypsin and chymotrypsin (p<0.05). Saponin and taurocholic acid significantly increased trypsin and chymotrypsin activity. Sodium cholate significantly increased chymotrypsin activity (p<0.05), but not the trypsin activity (p>0.05). Oxidizing agents, including hydrogen peroxide and sodium perborate, significantly decreased trypsin (p<0.05). Trypsin and chymotrypsin activity significantly decreased in the presence of SBTI, PMSF and ρ-Aminobenzamidine inhibitors (p>0.05). The inhibitors such as TPCK, pepstatinA, iodoacetic acid, EDTA and ß-mercaptoethanol did not significantly decrease the trypsin activity (p>0.05), but they significantly decreased chymotrypsin activity (p<0.05). Trypsin activity in the presence of TLCK showed a significant decrease (p<0.05), but  TLCK and pepstatin A  had no significant effect on chymotrypsin activity (p>0.05). 

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Spirulina platensis is an edible microalga with high protein content (60-70%). Presently, there is a rising interest to evaluate in vitro cytotoxic effect of edible protein after hydrolysis by the gastric protease. Unfortunately, despite widespread researches about the health effect of hydrolyzed proteins in dairy products, very few studies are available in the field of marine microalgae protein. Therefore, this research was aimed to investigate anticancer and antibacterial effects of the dominant protein of S. platensis after hydrolyzed by Trypsin and Chymotrypsin enzymes on Human colon adenocarcinoma cell and Escherichia coli, and Staphylococcus aureus, respectively. The results revealed that ̴ 20-22 kDa protein and its derived peptides decrease bacterial growth and <3kDa peptide fraction was able to significantly reduced SW480 cell viability.  Based on this study, we can conclude that Spirulina plantesis is a potential protein source in the future industrial production of functional peptides.