Fig. 3

a, b Effect of pH on ALR and ALR^A131K activities. ALR (a) and ALR^A131K (b) activities were assayed for 5 min at 30 °C and the indicated pHs using 20 mM l-alanine as substrate. For ALR, the maximum rates with and without acetate were 219 ± 3.61 and 217 ± 3.25 μmol/min mg, respectively (n = 3). For ALR^A131K, the maximum rates with and without acetate were 583 ± 0.593 and 591 ± 9.10 μmol/min mg, respectively (n = 3). Open circles, without acetate; filled circles, with 1 mM acetate. The buffers used were citrate (pH 4.0–5.5, MES (pH 5.5–7.0), Tris–HCl (pH 7.0–9.0) and carbonate (pH 9.0–11.0)