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 resi- dues involved in catalytic hydrogen evolution reaction (CHER) ofnucleic 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. Weassume that the peak P is connected with reduction ofguanine to 7,8-dihydroguanine, ofwhich reoxidation to gua- nine 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 ofdependences on experimental parameters such as neg- ative vertex potential and pH.