Figure 3.

Folding kinetics of the pre-RNA. (A) Folding reactions at 30°C were analyzed after 0–20 min in 3.25 or 6.0 mM MgCl₂ by native gel electrophoresis as described (22). The gel was run continuously during the experiment, so that samples loaded at 20 min have migrated a shorter distance. (B) Formation of native pre-RNA at 30°C. ■, 3.25 mM; ▴, 4.0 mM; ●, 6.0 mM MgCl₂. The data were fit to a first-order rate equation as described in Materials and Methods. For clarity, only the first 20 min of the reaction are shown. An additional slow kinetic phase can be resolved when ƒ_N(t) is monitored over 120 min (22). (C) Formation of intermediates (I). Symbols are as in B. The data were fit to equations with one or two exponential terms (see Materials and Methods).