FIGURE 3.

Thermal stabilization by selected tertiary motifs. (A) Kinetic profiles of ribozyme RzB in 10 mM (triangles, solid lines) or 2 mM (squares, dashed lines) MgCl₂ at four temperatures as follows: (blue) 37°C; (green) 50°C; (orange) 70°C; (red) 80°C. (B) Kinetic profiles of ribozyme RzB-0, following same symbols as in A. (C) Temperature dependence of initial rate, calculated as described in Materials and Methods. (Closed symbols) RzB; (open symbols) RzB-0; (triangles with solid lines) 10 mM MgCl₂; (squares with dashed lines) 2 mM MgCl₂. Reactions that gave no measurable rate are not plotted (e.g., RzB at 80°C in 2 mM MgCl₂).