Fig. 4

Characterization of EST4. a Substrate specificity of EST4 on various p-nitrophenyl esters. p-nitrophenyl esters of various lengths were assayed at 30 °C in 100 mM Tris–HCl buffer, pH 8.0. b Effect of pH on EST4 activity, measured at 30 °C for 5 min in 100 mM different buffers with varying pH values using p-NP butyrate as the substrate. The buffers used were citrate (solid square), phosphate (solid circle), Tris–HCl (solid triangle), and Glycine-NaOH (solid inverted triangle). c Effect of temperature on EST4 activity, measured at different temperatures for 5 min in 100 mM Tris–HCl buffer, pH 8.0. d Effect of temperature on EST4 stability. EST4 was incubated in 100 mM Tris–HCl buffer, pH 8.0, at 40, 45, 50, 55, or 60 °C for various durations, and residual activity was measured at 30 °C for 5 min. The maximal activity was defined as 100 % and the relative activity is shown as a percentage of maximal activity