High Performance Q Sepharose and Source PHE chromatography of Brucella suis urease. Column elautes were monitored for absorbance 280 nm (solid lines), and fractions were assayed for urease activity (solid circles), as described in Methods. A) High Performance Q Sepharose chromatography was performed using a NaCl gradient (dotted line); fractions with urease activity where precipitated with (NH4)2SO4 (1.5 M) and applied to the Source PHE column. B) Source PHE chromatography was performed using a (NH4)2SO4 gradient (dotted line). Urease was eluted in 180 mM of (NH4)2SO4.