FIG. 3.

Effect of temperature on the activity and stability of LAMY. (A) The temperature activity curves of purified LAMY (•) and BLA (○) (each at 0.18 U ml⁻¹) are shown. The reactions were done at the indicated temperatures for 10 min and at pH 8.5 in 50 mM Tris-HCl buffer. The values are shown as percentages of the specific activity of LAMY observed at 55°C, which is taken as 100%. (B) For determination of the thermostability of LAMY, the enzyme (1.8 U ml⁻¹) was heated at the indicated temperatures in the presence (at 50°C [□], 60°C [▵], and 70°C [○]) or absence (at 50°C [■] and 60°C [▴]) of 0.1 mM Ca²⁺ ions in 50 mM Tris-HCl buffer (pH 8.5). Samples (0.1 ml) were used for the determination of the residual activity under the standard conditions of the assay.