FIGURE 2. Time course of the cyclization reaction involving the final selected ribozyme, which contained only D and U residues.

The reaction mixture contained 20 nM RNA, 100 mM MgCl₂, 0.01% SDS and 30 mM 2-(N-cyclohexylamino)ethanesulphonic acid (CHES; pH 9.0), which was incubated at 23 °C. Products were separated in a 6% denaturing polyacrylamide gel. a, Phosphorimager scan of selected time points. b, Time course carried out to determine the maximum extent of reaction. Each data point is the average of three separate experiments, with the error bars corresponding to one standard deviation. The data were fitted to a single exponential to obtain a k_obs of 0.048 0.005 h^-1 and a maximum extent of reaction of 8.3%.