Abstract

An extracellular protease of Bacillus amyloliquefaciens S94 was purified to apparent homogeneity. The enzyme activity was strongly inhibited by general inhibitor for serine protease, PMSF, suggesting that the enzyme is a serine protease. The purified enzyme activity was inhibited by leucine peptidase inhibitor, bestatin, suggesting that the enzyme is a leucine endopeptidase. The maximum proteolytic activity against different protein substrates occurred at pH 10, 45℃ (protein substrate) and pH 8, 45℃ (synthetic substrate). The purified enzyme was specific in that it readily hydrolyzed substrates with Leu or Lys residues at P1 site. The protease had characteristics of a cold-adapted protein, which was more active for the hydrolysis of synthetic substrate in the range of 15℃ to 45℃, specially at low temperature.

• Keywords: Bacillus amyloliquefaciens; multifunctional endopeptidase; serine protease; cold active enzyme.