Purification and Characterization of a Novel Low-Temperature Protease BsLT with High Potential for Hydrolyzing Wheat Gluten

Low-temperature protease has the characteristics of a high reaction rate at low temperatures. Here, a new low-temperature protease BsLT (17 kDa) was extracted from <i>Bacillus subtilis</i> XZ1-5 and purified with a final purification fold of 10.08 times and a specific activity of 59,675.22 U/mg. The optimum temperature and pH were 20 °C and 7, respectively. The activity of BsLT was significantly enhanced by 1% Tween-80, 1% Tween-20, and 10% DMSO. But it was less tolerant to Cu²⁺, Fe³⁺, and H₂O₂. The optimum substrate was casein. The <i>K</i>_m and <i>V</i>_max values were 7.14 and 312.5 mg/(min·mL), respectively. After hydrolysis by BsLT, the molecular structure of wheat gluten changed significantly. The solubility of wheat gluten increased to 150 mg/mL, OH radical scavenging ability increased to 65%, DPPH radical scavenging ability increased to 79%, and ABTS radical scavenging ability increased to 60%, which shows BsLT has the potential for further application in food processing.