Marwa Bouhlel, Faical Brini and Walid Saibi*
Proteases are hydrolytic biocatalysts that catalyze peptide linkage/cleavage reactions at the level of proteins and peptides with different degrees of specificity. The serine proteases are the most commercially available enzyme in the world market and are researched for their industrial uses. We report here the extraction, the biochemical characterization of a novel serine protease with milk-clotting and Leather activities (named PAA) from Agave americana. Indeed, PAA was purified at homogeneity after three purification steps involving ammonium sulfate precipitation at 80%, ethanol fractionation and finally, gel filtration coupled to HPLC system. Their optimal activity was showed at 60°C and 7.8 units of pH. PAA has an apparent molecular weight of approximately 35 kDa estimated by sodium dodecyl sulfate polyacrylamide gel electrophoresis and size exclusion chromatography. In addition, the PAA irreversible inhibition by the Diisopropyl-Fluoro-Phosphate and the Phenyl-Methyl-Sulfonyl-Fluoride proves it’s belonging to the serine protease family. In another hand, the PAA autodigestion level is estimated to 20% after 30 days of self-incubation, the hydrolysis percentage of casein with PAA is about 22.9%, their efficiency in milk-clotting will lead to their plausible applied in various biotechnological tools related to agrofood industries. Also, the PAA proves an excellent capability in Leather Industry.
