Activation and Alteration of Base Selectivity by Metal Cations in the Functionality-Transfer Reaction for RNA Modification

Previously, we reported that the 2-methylidene-1,3-diketone unit of 6-thioguanosine transferred selectively to the amino group of cytosine at pH 7.0 and that its selectivity was changed to the guanine base at pH 9.6. In this study, it was found that the functionality-transfer reaction enhanced selectivity for the guanine base in the presence of divalent transition metal cations such as Ni²⁺ and Co²⁺ at pH 7.4.