en Biotechnology Biotechnology پژوهشي Orginal research papers <span lang="TR" style="font-size:11.0pt"><span calibri="" style="font-family:"><span style="color:black">The viscera of narrow-barred Spanish mackerel (<i>Scomberomorus commerson</i>) fish contains abundant alkaline and acidic proteases that can be isolated using various methods. We purified pepsinogen from <i>S. commerson</i> viscera using ammonium sulfate precipitation, Sephadex G-50 gel filtration, and DEAE-cellulose ion-exchange chromatography. Two peaks corresponding to pepsinogen were observed during gel filtration and further purified using ion-exchange chromatography. Additionally, we investigated the effects of polyethylene glycol graphene oxide (GO-PEG) at a concentration of 3 mg/mL on enzyme activity and stability. Results demonstrated a significant enhancement in enzyme activity and increased stability at higher temperatures compared to the control group. These findings suggest that GO-PEG can improve enzyme production and stability. However, purified pepsin was found to be inactive in the presence of 0.1 M pepstatin A. In conclusion<i>, S. commerson</i> viscera offers a valuable source for pepsin purification. The purification process involving ammonium sulfate precipitation, gel filtration, and ion-exchange chromatography successfully obtained purified pepsinogen. The use of GO-PEG exhibited promising potential in enhancing enzyme activity and stability, highlighting the role of nanosheets in improving enzyme thermal stability.</span></span></span> Fish viscera, Graphene oxide, Pepsin purification, Thermal stability, Narrow-barred Spanish mackerel 757 779 http://jifro.ir/browse.php?a_code=A-10-3975-1&slc_lang=en&sid=1 S.R. Shobar reza.shobar@yahoo.com 100319475328460056817 100319475328460056817 No Seafood Processing Department, Marine Sciences Faculty, Tarbiat Modares University, Noor, Iran M. Rezaei rezai_ma@modares.ac.ir 100319475328460056818 100319475328460056818 Yes Seafood Processing Department, Marine Sciences Faculty, Tarbiat Modares University, Noor, Iran S. Naghdi Shahab_naghdi@modares.ac.ir 100319475328460056819 100319475328460056819 No Seafood Processing Department, Marine Sciences Faculty, Tarbiat Modares University, Noor, Iran A. Taghavi Moghadam taghavi_ahmad@yahoo.com 100319475328460056820 100319475328460056820 No Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization, Ahvaz, Iran