pH and Temperature Sensitivity of Endogenous Proteases in pH 7-OB
pH 7-OB was sticky, so it was mixed with the same volume of precooled DI water. Then the pH 7-OB suspension was adjusted to pH 3, 4, 5, 6, 7, 8, and 9 by 1 M HCl or 1 M NaOH solution. These samples were incubated in a 50 °C water bath for 2 h. The obtained samples were used for Tricine–SDS–PAGE, TCA–NSI, and free amino acid analyses.
Then the pH 7-OB suspension was adjusted to pH 5, and incubated in 30, 40, 50, 60, 70, and 80 °C water baths for 1 h. The obtained samples were used for Tricine–SDS–PAGE analysis.