Figure 7.

Alr3090 (KatB) is a robust Mn-catalase. A, Purified KatB protein was resolved on 10% nondenaturing native PAGE and visualized by staining with Coomassie Brilliant Blue. Similar gel profiles were obtained in four different experiments and a representative image is shown. B, Size exclusion chromatography profile of the purified KatB protein using Superdex 200 10/300 GL column pre-equilibrated with buffer (20 mm Tris, 50 mm NaCl, pH 7.5). C, The recombinant KatB protein was assayed for catalase activity on zymogram. The amount of the KatB protein is indicated. D, The catalase activity of KatB protein was measured (at room temperature) by monitoring the decrease in A₂₄₀ (OD₂₄₀). E, Catalase activity of the purified KatB protein was monitored at different concentrations of NaCl as indicated. The rate of KatB activity in the absence of NaCl was considered as 100%, and other rates were calculated accordingly. Error bars represent SE (n = 5). F, The purified KatB protein (2 µg) was incubated in the presence of different temperatures for 10 min. Subsequently, employing H₂O₂ as substrate, the catalase activity was measured (at room temperature) by monitoring the decrease in A₂₄₀. The activity of KatB incubated at room temperature was considered to be 100%, and the other rates were calculated accordingly. Error bars represent SE (n = 4).