Catalytic and redox activity of nucleic acids at mercury electrodes: Roles of nucleobase residues

Abstract

Using a series of specifically designed oligonucleotides we have identified adenine and cytosine nucleobases as residues involved in catalytic hydrogen evolution reaction (CHER) of nucleic acids at the hanging mercury drop electrode (HMDE). Due to the CHER, nucleic acids yield catalytic peak HNA allowing their label-free and reagent-less analysis at low concentrations. Additionally, our results suggest that presence of the electroactive bases (adenine and cytosine) facilitates guanine reduction which is for the first time linked to a signal measurable at the HMDE — the peak P. We assume that the peak P is connected with reduction of guanine to 7,8-dihydroguanine, of which reoxidation to guanine is detected at the electrode by the earlier described anodic peak G. Processes connected with the above mentioned signals were studied using cyclic voltammetry by inspection of dependences on experimental parameters such as negative vertex potential and pH.