Purification and characterization of a protease from the visceral mass of Mytella charruana and its evaluation to obtain antimicrobial peptides

•A protease was isolated from Mytella charruana visceral mass.•The enzyme (pI 4.1, 83.1 kDa) is a trypsin-like protease with optimal temperature of 40 °C.•Its trypsin-like activity was stable at pH range 3.0–9.0.•Sequenced similarities with tropomyosin and myosin from molluscs were detected.•The protease was able to hydrolyze casein and the hydrolysate inhibited bacterial growth. This work describes purification of a protease from the visceral mass of the mussel Mytella charruana as well as evaluation of its ability to hydrolyze milk casein to generate antimicrobial peptides. The enzyme showed pI of 4.1 and a single polypeptide band of 83.1 kDa after SDS-PAGE. Sequence similarities with tropomyosin and myosin from mollusks were detected. The protease showed a trypsin-like activity with optimal temperature of 40 °C and stability in a wide pH range (3.0–9.0). Km was 4.28 ± 0.34 mM of the synthetic substrate N–benzoyl–dl-arginyl-ρ-nitroanilide, whereas Vmax was 0.056 ± 0.001 nmol min−1. The enzyme hydrolyzed casein, and the hydrolysate inhibited the growth of Escherichia coli, Micrococcus luteus, Bacillus subtilis, and Klebsiella pneumoniae at a minimal inhibitory concentration of 5.0 µg mL−1. In conclusion, the visceral mass of M. charruana contains a trypsin-like protease that can generate peptides from casein that have a bacteriostatic effect.