Figure 4.

DNA-catalyzed cleavage of RNA under laboratory conditions. 5′-³²P-labeled RNA substrate (S), having the sequence 5′-GGAGAGAGA⋅UGGGUGCG-3′, was cleaved by the corresponding 10-23 DNA enzyme to generate a single-labeled product (P). Reaction conditions: 1 μM substrate, 10 nM enzyme, and 50 mM MgCl₂ (pH 8.0) at 37°C; sampled at 0, 1, 2, 5, 10, and 20 min. Reaction products were separated by electrophoresis in a denaturing 20% polyacrylamide gel, an autoradiogram of which is shown. The ladder at the right was produced by partial alkaline hydrolysis of the substrate; at short oligonucleotide lengths, products terminated by a 2′ or 3′ phosphate have slightly faster mobility compared with those with a 2′,3′-cyclic phosphate.