FIGURE 5.

Effects of temperature, pH, NaCl, and divalent metals on rNitAly activity. A, temperature dependence of alginate lyase activity of rNitAly. Enzyme reactions were conducted in a solution containing 10 mm sodium phosphate (pH 6.0), 1 m NaCl, 0.1 mg/ml BSA, 0.005 mg/ml rNitAly, and 0.5% (w/v) polyM for 15 min at the indicated temperatures. Relative activity of 100% was equivalent to 1,620 units/mg. B, pH dependence of the alginate lyase activity of rNitAly. Assays were performed as described for A, except that reaction mixtures were incubated at 50 °C for 15 min in 10 mm sodium acetate for pH 4.0–5.1 (open circles), 10 mm sodium phosphate for pH 5.7–7.4 (closed circles), 10 mm Tris-HCl for pH 8.1–8.5 (closed triangles), and 10 mm glycine-NaOH for pH 9.2–10.4 (open triangles). Relative activity at 100% was equivalent to 1,230 units/mg. C, NaCl dependence of the alginate lyase activity of rNitAly. Assays were performed as described for A at 50 °C, except that different concentrations of NaCl were used as indicated. Relative activity at 100% was equivalent to 1,430 units/mg.