The protein-containing fractions were incubated at 4 °C with 0.5 mg of TEV protease (produced in-house) per 1 L culture for 3 h at 25 °C to cleave the tag and then dialyzed overnight at 4 °C against 25 mM Tris-HCl [pH 8], 400 mM NaCl, 10 mM imidazole...