Purification and biochemical characterization of a novel intestinal protease from Scorpaena notata

A new protease was isolated from the intestine of small red scorpionfish. After ammonium sulfate precipitation, the enzyme was purified to homogeneity by a two-step chromatography with 6.69% recovery and fivefold increase in specific activity. The molecular weight of the protease was about 24kDa as estimated by size exclusion chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme optimum pH and temperature were pH 10.0 and 40 degrees C, respectively. The protease was stable at temperatures below 40 degrees C and over a broad pH range (8.0-11.0). The K-m and K-cat values were 0.36mmolL(-1) and 1.61s(-1), respectively. Interestingly, the enzyme presented specificity for casein, egg albumin, bovine serum albumin, and gelatin with obtained degrees of hydrolysis ranging from 3.14% to 6.58%, after 2h of hydrolysis. Moreover, gluten hydrolysate analysis confirmed protein hydrolysis and solubilization. These results suggested the potential use of the protease in the preparation of food protein hydrolysates with interesting properties.