crib220u270rib220u18504i 30 4 buffer (60 ml) to buffer + 0.4 M NaCl (60 ml) 6 Column chromatography 0.31 M NaCl anion exchange column chromatography (TOSOH CORPORATION, Super Q TOYOPEARL 650M) 20 mM Tris-HCl, pH 8.0 3 _