Proteases from Canavalia ensiformis: Active and Thermostable Enzymes with Potential of Application in Biotechnology.

Extracts of leaves, seeds, roots, and stem from a tropical legume, C. ensiformis, were prepared employing buffers and detergent in aqueous solution. Leaf extracts had the highest protein content and the most pronounced peptidase activity with optimal pH in the neutral to alkaline range. All extracts exhibited peaks of activity at various pH values, suggesting the presence of distinctive classes of proteases. N-α-Tosyl-L-arginine methyl ester hydrolysis was maximal at 30°C to 60°C and peptidase activity from all extracts presented very good thermal stability after 24 h incubation at 70°C. C. ensiformis proteases exhibited molecular masses of about 200-57, 40-37, and 20-15 kDa by SDS-PAGE analysis. These enzymes cleaved hemoglobin, bovine serum albumin, casein, and gelatin at different levels. Serine and metalloproteases are the major proteases in C. ensiformis extracts, modulated by divalent cations, stable at 1% of surfactant Triton X-100 and at different concentrations of the reducing agent β-mercaptoethanol. Thus, C. ensiformis expresses a particular set of proteases in distinctive organs with high activity and stability, making this legume an important source of proteases with biotechnological potential.