Effects of temperature and pH on the structure of a protease from Lactobacillus brevis R4 isolated from Harbin dry sausage and molecular docking of the protease to the meat proteins

Abstract Spectroscopy and molecular dynamics were utilized to evaluate the influence of pH and temperature on the structural characteristics of Lacobacillus brevis R4 protease isolated from Harbin dry sausage. The protease has a stable spatial structure at pH 7 and 40 °C, and the extended secondary structure of the protease was identified. The structure of the protease can be changed or denatured at pH 8 and 70 °C, the changes at which predominantly manifested as changes in the secondary structure, such as α-helices, β-sheets, β-turns and random coils. In addition, carbonyl vibration, –NH vibration, C–H stretching vibration and disulfide bonds were present in the L. brevis R4 protease at various pH and temperatures. Molecular docking showed that the protease can interact with the myosin light chain, myosin heavy chain and troponin, which demonstrates the protease may accelerate the degradation of meat proteins, promote meat tenderness and then improve the flavor and quality of Harbin dry sausages.