FIG 6.

Properties of the mature enzymes. (A) SDS-PAGE analysis of the purified mature enzymes. (B) Salt dependence of enzyme activity. The azocaseinolytic activity of the mature enzymes was measured at 40°C in buffer A containing different concentrations of NaCl. (C) Enzymatic hydrolysis of suc-AAPF-pNA. Enzyme activity was measured at 40°C using suc-AAPF-pNA (0.1 mM) as the substrate in buffer A containing 3.5 M NaCl. (D and E) Heat inactivation of the mature enzymes. The mature enzymes (3 μg/ml) were incubated at 60°C in buffer A (50 mM Tris-HCl, 10 mM CaCl₂ [pH 8.0]) containing 3, 4, or 5 M NaCl. At the indicated times, aliquots were removed and subjected to azocaseinolytic-activity assay (D) and SDS-PAGE analysis (E). Residual activity is expressed as a percentage of the original activity of each sample (D). Values (B, C, and D) are expressed as the means ± SDs (bars) of three independent experiments.