Partial characterization of digestive proteases in the river prawn Macrobrachium americanum (Spence Bate, 1868) (Decapoda: Caridea: Palaemonidae) in Mexico

We characterized the digestive enzymes in adults of Macrobrachium americanum (Spence Bate, 1868) in southeastern Mexico. The digestive enzyme extracts were made from the specimens' hepatopancreas. Alkaline proteases, trypsin, chymotrypsin, carboxypeptidase A, leucine aminopeptidase, lipases, a-amylase and alkaline phosphatase activities were determined, as well as the percentage of inhibition, pH, and temperature stabilities through biochemical and electrophoretic techniques. The maximum digestive activity of proteases was at 35 degrees C and pH 11. Alkaline digestive proteases were highly stable at pHs 4, 9 and 11 at 55 degrees C after 30 min pre-incubation. PMSF inhibited two bands with proteolytic activity (35.1 and 23.2 kDa), and SBT1 inhibited all bands, including the one with the highest molecular weight (64.2 kDa). We concluded that enzymes in M. americanum coincide with those of omnivorous decapods with a tendency to carnivory.