Biochemical characterization of a semi-purified aspartic protease from sea catfish Bagre panamensis with milk-clotting activity
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Pepsin from stomach of Bagre panamensis was semi-purified and biochemically characterized. The acid proteolytic activity and purification fold were 3875 U/mg protein and 91.85, respectively, after purification process. The optimum pH and temperature for semi-purified protease were 2–3 and 65 °C, respectively. The enzyme activity was stable after heating proteases at 50 °C for 120 min, but only 30% residual activity was detected after heating at 65 °C for 30 min. SDS-PAGE analysis showed two proteins bands after dialysis (26.1 and 38.6 kDa). Only the band of 38.6 kDa had proteolytic activity, which was inhibited using pepstatin A. Organic solvents, surfactants and reducing agents affect the proteolytic activity at different extent; however, metal ions or EDTA have no impact on protease activity. The semi-purified protease exhibited milk coagulant activity, with a maximum activity at 45 °C. The obtained results highlight the potential biotechnological use of B. panamensis pepsin.
KeywordsProteases Milk clotting activity Catfish Pepsin Protein purification By-products
The authors would like to thank to MC Gissel Rios and Reyna Tiznado for her laboratory assistance and MC Jesús Martín Moreno Hernandez for his advices for milk-clotting assays. Also, the authors thank María Elena Sánchez Salazar for her editorial work in English. This work has been elaborated as an activity from thematic research network of CONACYT: “RED 12.4, Para reducir y valorizar las pérdidas y desperdicios de alimentos: Hacia sistemas alimentarios sostenibles (No. 294768)”.
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Conflict of interest
The authors declare no conflict of interest.
Human and animal rights statement
This article does not contain studies with animals subjects performed by the any of the authors.
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