Comparison of metal-ion-dependent cleavages of RNA by a DNA enzyme and a hammerhead ribozyme.

Joyce's DNA enzyme catalyzes cleavage of RNAs with almost the same efficiency as the hammerhead ribozyme. The cleavage activity of the DNA enzyme was pH dependent, and the logarithm of the cleavage rate increased linearly with pH from pH 6 to pH 9 with a slope of approximately unity. The existence of an apparent solvent isotope effect, with cleavage of RNA by the DNA enzyme in H(2)O being 4.