Figure 4.
Self-ligation occurs in a helical context. (A) Effect of changing the substrate-binding portion of the ribozyme and/or the sequence of the RNA substrate. Catalytic rates were measured in the presence of 50 mM MgCl2 at 50°C. (B) The regiospecificity of ligation was determined in a reaction with two oligonucleotide substrates, one containing 32P-labeled guanylate residues. The ligation products were purified, digested with RNase T2, mixed with unlabeled G(2′→5′)Up (dotted circle), and analyzed by two-dimensional thin-layer chromatography.