Protease Inhibitor Assay
This was conducted according to the method by Wilson and Tan-Wilson (2015). pH 7-OB suspension was adjusted to pH 3–9, and they were incubated with 2 μM pepstatin A or 0.5 mM AEBSF or no inhibitor (control) for 1 h on ice. Then they were incubated at 50 °C for 1 h. As for pH 9.5-OB suspension, the same procedures were conducted except that the incubation time was 2 h. The obtained samples were used for the Tricine−SDS−PAGE analysis.