Following sample application, the following gradient was applied: 2 mine8 min; 0%e30% Buffer B (50 mM MES, 1 M NaCl, pH 6.4), 8 mine40 min 30%e55% Buffer B, 40 mine43 min; 55%e100% Buffer B. Eluted protein was detected by measuring absorbance of at 280 nm.