A divalent metal-dependent self-cleaving DNAzyme with a tyrosine side chain

The enzymatic incorporation of a phenol-modified 2′-deoxyuridine triphosphate gave rise to a modified DNA library that was subsequently used in an in vitro selection for ribophosphodiester-cleaving DNAzymes in the presence of divalent zinc and magnesium cations. After 11 rounds of selection, cloning and sequencing resulted in 14 distinct sequences, the most active of which was Dz11-17PheO. Dz11-17PheO self-cleaved an embedded ribocytidine with an observed rate constant of 0.20 ± 0.02 min−1 in the presence of 10 mM Mg2+ and 1 mM Zn2+ at room temperature. The activity was inhibited at low concentrations of Hg2+ cations and somewhat higher concentrations of Eu3+ cations.