FIGURE 3.

Enzymatic properties of purified SdG5A. (A) Effect of temperature on the catalytic activity. The temperature profile was determined in C₄H₂O₇–Na₂HPO₄ buffer (pH 6.5) at different temperatures ranging from 0 to 70°C. The activity of the enzyme at 45°C was taken as 100%. (B) Effect of temperature on protein stability. To assess the thermostability, the enzyme was incubated at 25°C (pink), 35°C (blue), and 45°C (green). The residual activity was measured at pH 6.5 and 45°C. The activity before the incubation was taken as 100%. (C) Effect of pH on the catalytic activity. The pH profile was determined in 50 mM C₄H₂O₇–Na₂HPO₄ buffer at pH range of 2.5–8.0 (blue) and 50 mM glycine-NaOH buffer at a pH range of 8.0–11.0 (pink) at 45°C. The maximum activity obtained at pH 6.5 was considered as 100%. (D) Effect of pH on protein stability. The pH stability was determined by incubating the enzyme in 50 mM C₄H₂O₇–Na₂HPO₄ buffer at pH range of 2.5–8.0 (blue) and 50 mM glycine-NaOH buffer at pH range of 8.0–11.0 (pink) for 1 h at 4°C and the residual activity was measured at pH 6.5 and 45°C. The activity before the incubation was taken as 100%. (E) Effect of different metal ions on the catalytic activity. The activity of the enzyme with no addition was defined as 100%. (F) Effect of NaCl concentrations on the catalytic activity. The activity of the enzyme with no addition was defined as 100%. Each value represents the mean of three independent measurements (mean ± standard derivation).