FIGURE 6.

YkuE purification and stability in the presence of different protease and hydrolase inhibitors. YkuE was purified from overproducing cells of the native host B. subtilis as described under “Experimental Procedures.” SDS-PAGE analysis of the YkuE-StrepII protein (∼35 kDa) was performed with a freshly purified sample obtained directly after elution from the Strep-Tactin column (lane 1), or with samples obtained after 20 h of incubation at 4 °C in the presence of either 1 mm N-ethylmaleimide (lane 2), 1 mm phenylmethylsulfonyl fluoride (lane 3), 10 mm EDTA (lane 4), or 1 mm EDTA (lane 5). Degradation bands observed upon protein incubation in buffered solution were identified by mass spectrometry to be part of the original full-length protein.