Fig. 4

The pH stability of SOD _Ss and rSODSs (a). The residual SOD activity was evaluated after incubation at different pH values at 25 °C for 90 min and calculated as the percentage of the maximum activity. The buffer systems used were 50 mM sodium citrate (pH 3.0–8.0), Tris–HCl (pH 8.0 and 9.0), or glycine-NaOH (pH 9.0 and 10.0). Effects of inhibitors, detergents, and denaturants on SOD activity (b). Each enzyme was incubated with each inhibitor, detergent, denaturant and organic medium at various final concentrations in 50 mM sodium phosphate buffer (pH 7.8) at 25 °C for 30 min. The reaction mixture without inhibitor, detergent, denaturant or organic medium was used as a control and was defined as 100 %. The residual activities were measured by the standard assay as described in the “Methods”