Fig. 6. Kinetic folding analysis. (A) Folding of 3′-end-labeled G11 D (left) or Pre (right) was initiated at time zero by the addition of MgCl₂ to a final concentration of 20 mM. ONOOK was added to the RNA at the times indicated on the x-axis (and up to 300 s, data not shown) after the addition of MgCl₂. Regions of protection are indicated by black bars. (B) The fraction of maximal protection versus time after addition of MgCl₂ is plotted for nucleotides 686, 701, 721 and 756 using diamonds, squares, triangles and circles, respectively, for G11 Pre (filled symbols) and D (open symbols).