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

The enzymatic incorporation of a phenol-modified 2[prime or minute]-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.