Figure 4. The structural-kinetic model common to all of the analyzed temperatures that was resolved for the Mg²⁺-induced folding of the Tetrahymena ribozyme.

(A) The model configuration includes the unfolded (U), and folded (F) states, and two intermediates (I1 and I2). The structured regions of each species are modeled from the •OH reactivity patterns and rendered as bold ribbons. The kinetic rate constants are determined for all forward reactions (black arrows) by constraining all other folding reaction (grey arrows) as indicated in the Materials and Methods . The folding rates determined at 40°C are shown (s⁻¹). (B) From the top to the bottom, the calculated time evolution of U, I1, I2 and F are shown from 21.5 and 51°C using the color bar insert to the top panel.