FIG. 3.

The effects of Co²⁺ and Zn²⁺ ions on the activity of the P. furiosus aminoacylase after EDTA treatment. The enzyme (29 μg in 50 mM bis-Tris, pH 6.5), was incubated at 80°C for 30 min with various concentrations of either ZnCl₂ (solid symbols) or CoCl₂ (square symbols) and then assayed under standard conditions (in the absence of added metal ions). The assay mixture contained aminoacylase (2.9 μg), N-acetyl-l-methionine (30 mM), and 50 mM bis-Tris buffer, pH 6.5. The 100% activity level corresponds to 200 U/mg.