Purification and characterization of detergent-compatible protease from Aspergillus terreus gr

The possibility of using Aspergillus terreus protease in detergent formulations was investigated. Sodium dodecyl sulfate (SDS) and native polyacrylamide gel electrophoresis indicated that the purified alkaline protease (148.9 U/mg) is a monomeric enzyme with a molecular mass of 16 ± 1 kDa. This was confirmed by liquid chromatography-mass spectrometry. The active enzyme degraded the co-polymerized gelatin. The protease demonstrated excellent stability at pH range 8.0-12.0 with optimum at pH 11.0. It was almost 100 % stable at 50 °C for 24 h, enhanced by Ca²⁺ and Mg²⁺, but inhibited by Hg²⁺, and strongly inhibited by phenylmethyl sulfonyl fluoride. It showed maximum activity against casein followed by gelatin; its V_max was 12.8 U/ml with its corresponding K_M of 5.4 mg/ml. The proteolytic activity was activated by Tween-80, Triton-100 and SDS, and remained unaltered in the presence of H₂O₂ and NaClO. The enzyme exhibited higher storage stability at 4, 28 and -20 °C. It was stable and compatible to the desired level in the local detergents. The addition of the protease to the Super wheel improved its blood stain removal. The isolated protease can thus be a choice option in detergent industry.