1.5.1.34 | cells centrifuged, washed with PBS (pH 7.4), resuspended in lysis buffer (50 mM Tris-HCl, pH 7.5), disrupted by sonication, centrifugation, supernatant filtered (0.45 microm), applied to a column with nickel-NTA beads, eluted (50 mM Tris-HCl, pH 7.5), active fractions pooled, concentrated, and exchanged into 50 mM sodium phosphate, pH 6.8, ultrafiltration, applied to a cation-exchange chromatography HS20 column, eluted with salt gradient at pH 6.8, concentration by ultrafiltration, gel-filtration chromatography with Superdex 200 column in 50 mM Tris-HCl, pH 8.0, concentration of eluted fractions in 20 mM Tris-HCl, pH 8.0, by ultrafiltration |