FIG 6.

(A) Effects of temperature on the activities of Tc-ChiD(ΔS) and Tc-ChiD(ΔBD). The chitinase activities were determined at different temperatures (50 to 95°C) by using the Schales procedure, as described in Materials and Methods. (B) Effects of pH on the activities of Tc-ChiD(ΔS) and Tc-ChiD(ΔBD). The chitinase activities were determined at different pH conditions, as described in Materials and Methods. Symbols: dark green squares, sodium citrate (pH 3.0 to 5.0); blue triangles, sodium phosphate (pH 4.5 to 6.0); light green diamonds, MES (pH 6.0 to 7.0). (C) Thermostabilities of Tc-ChiD(ΔS) and Tc-ChiD(ΔBD). Purified enzymes were incubated in 50 mM Tris-HCl (pH 7.5) supplemented with 150 mM NaCl at 80°C (blue diamonds), 90°C (red squares), and 100°C (green triangles) for various time intervals. The residual activities were determined at 85°C.