FIG. 5.

(A) Thermal stabilities of rSapSh (•) and subtilisin Carlsberg (■). The enzymes were incubated at 60°C in 50 mM Tris-HCl buffer (pH 9.0) supplemented with 2 mM CaCl₂ for different periods of time, and the residual activities were determined at 60°C with AAPF as the substrate. (B) Denaturation of rSapSh (•) and subtilisin Carlsberg (■) by urea. The enzymes were incubated with various concentrations of urea for 30 min, and then the reactions were started by adding AAPF.